Iron Curtain – This phrase was coined after World War II by Prime Minister Winston Churchill of Great Britain to describe the rise of Russian influence over Eastern Europe. Churchill found the rigid censorship of the citizenry and the closing of borders frightening. In a visit to the United States in 1946, he expressed his disdain in a speech on 5 March at Fulton, Missouri, where he was to accept an honorary degree from Westminster College.

From Stettin in the Baltic to Trieste in the Adriatic, an iron curtain has descended across the continent. Behind that line lie all the capitals of the ancient states of central and eastern Europe, Warsaw, Berlin, Prague, Vienna Budapest, Belgrade, Bucharest, and Sofia, all the famous cities and the populations around them lie in what I might call the Soviet sphere, and all are subject, in one form or another, not only to Soviet influence but to a very high and in some cases increasing measure of control from Moscow. (A Hog on Ice & Other Curious Expressions by Charles Earle Funk ©1948)

To Give Short Shrift To – This phrase means to cut short; to make quick work of. The phrase comes to us from Shakespeare’s The Tragedy of King Richard III, Act Iv, scene 4. In the play, the Duke of Gloucester (later to be Richard III) has sentenced to death one Lord Hastings, but he Ratcliff interrupts Gloucester’s declarations. Ratcliff says: “Dispatch, my lord; the duke would be at dinner: Make a short shrift; he longs to see your head.” Ratcliff is suggesting the criminal should not be given an infinite amount of time to confess (or ‘shrift’). To speed up the executions in the 17th Century, “short shrift” became a synonym for “least possible delay.” (Heavens to Betsy & Other Curious Sayings by Charles Earle Funk ©1955)

Mind Your Ps and Qs – This phrase means to be on one’s best behaviour; be careful of one’s language.
Ps and Qs are just the plurals of the letters P and Q. There is some disagreement amongst grammarians about how to spell Ps and Qs – either upper-case or lower-case and either with or without an apostrophe.
Doubts also exist as to the original meaning. Francis Grose, in his 1785 edition of The Dictionary of the Vulgar Tongue, defines it like this:
“To mind one’s P’s and Q’s; to be attentive to the main chance.”

The date of the coinage of ‘mind your Ps and Qs’ is uncertain. There is a citation from Thomas Dekker’s play, The Untrussing of the Humorous Poet, 1602, which appears to be the earliest use of the expression:

Afinius: …here’s your cloak; I think it rains too.
Horace: Hide my shoulders in’t.
Afinius: ‘Troth, so thou’dst need; for now thou art in thy Pee and Kue: thou hast such a villanous broad back…

‘Pee and Kue’ in that citation seem to be referring to a form of clothing, but that is somewhat ambiguous. It is also not clear that the ‘Pee and Kue’ in Dekker’s work are the same as those in ‘mind one’s Ps and Qs’. Dekker later used the term in West-ward Hoe, a joint work with John Webster, 1607:

At her p. and q. neither Marchantes Daughter, Aldermans Wife, young countrey Gentlewoman, nor Courtiers Mistris, can match her.

In that piece it is less apparent that ‘p. and q.’ refer to a form of clothing.

So, both the spelling and meaning of the phrase are debatable. Now we come to what is really uncertain – the derivation. Nevertheless, it is one of those phrases of which many people are sure they know the origin. When such folk are pressed, what they usually mean is that the person they first heard explain the origin had made a random choice from the list of proposed derivations below: ‘Mind your Ps and Qs’ probably derives from one of these:

1. Mind your pints and quarts. This is suggested as deriving from the practice of chalking up a tally of drinks in English pubs (on the slate). Publicans had to make sure to mark up the quart drinks as distinct from the pint drinks. This explanation is widely repeated, but there is little to support it, apart from the fact that pint and quart begin with P and Q.
2. Advice to printers’ apprentices to avoid confusing the backward-facing metal type lowercase Ps and Qs, or the same advice to children who were learning to write. Nevertheless, the fact that handmade paper was an expensive commodity and that the setting of type in early presses was very time comsuming makes the printing story a strong candidate. The fact that type had to be set upside down and backwards made the need for a warning to be careful doubly appropriate.
3. Mind your pea (jacket) and queue (wig). Pea jackets were short rough woollen overcoats, commonly worn by sailors in the 18th century. Perruques were full wigs worn by fashionable gentlemen. It is difficult to imagine the need for an expression to warn people to avoid confusing them.
‘Pee’, as a name for a man’s coarse coat, is recorded as early as 1485, so it is possible that that is what Dekker was referring to in his 1602 citation. If so, that usage long predates all others and we have the definitive origin of ‘pee and kue’. ‘Kue’ or ‘cue’ as the name of a man’s wig isn’t known until well after 1602 though, so it still isn’t certain what Dekker meant by it.
4. Mind your pieds (feet) and queues (wigs). This is suggested to have been an instruction given by French dancing masters to their charges. This has the benefit of placing the perruque in the right context – as long as we accept the phrase as being originally French. However, there’s no reason to suppose it is from France and no version of the phrase exists in French.
5. Another version of the ‘advice to children’ origin has it that ‘Ps and Qs’ derives from ‘mind your pleases and thank-yous’.’ That is widely touted as an origin but seems to be a back-formation, that is, an explanation fitted to explain the phrase after it was coined in some other context. ‘Pleases and thank-yous’ does not appear to lead to ‘Ps and Qs’. (Phrases.org.uk)

Nepenthe – is a medicine for sorrow, literally an anti-depressant – a “drug of forgetfulness” mentioned in ancient Greek literature and Greek mythology, depicted as originating in Egypt.The carnivorous plant genus Nepenthes is named after the drug nepenthe.
The word nepenthe first appears in the fourth book of Homer’s Odyssey:

ἔνθ᾽ αὖτ᾽ ἄλλ᾽ ἐνόησ᾽ Ἑλένη Διὸς ἐκγεγαυῖα:
αὐτίκ᾽ ἄρ᾽ εἰς οἶνον βάλε φάρμακον, ἔνθεν ἔπινον,
νηπενθές τ᾽ ἄχολόν τε, κακῶν ἐπίληθον ἁπάντων.
(which means)
Then Helen, daughter of Zeus, took other counsel.
Straightway she cast into the wine of which they were drinking a drug
to quiet all pain and strife, and bring forgetfulness of every ill.
Odyssey, Book 4, v. 219–221 (Wikipedia)

Figuratively, nepenthe means “that which chases away sorrow”. Literally it means ‘not-sorrow’ or ‘anti-sorrow’: νη, ne, i.e. “not” (privative prefix), and πενθές, from πένθος, penthos, i.e. “grief, sorrow, or mourning”. In the Odyssey, in the passage quoted above, nepenthes pharmakon (i.e. an anti-sorrow drug) is a magical potion given to Helen by Polydamna the wife of the noble Egyptian Thon; it quells all sorrows with forgetfulness.

Keep a Stiff Upper Lip – This phrase has come to mean to remain resolute and unemotional in the face of adversity, or even tragedy.
This is such a clichéd expression that it is difficult to imagine doing anything else with a stiff upper lip apart from keeping it. If you try to hold your upper lip stiff your facial expression will appear aloof and unsmiling, betraying little of any feeling you might be experiencing. That demeanour is the source of ‘keep a stiff upper lip.’ The phrase is similar to ‘bite the bullet,’ ‘keep your chin up,’ and (to the amusement of many Americans) ‘keep you pecker up.’ It has become symbolic of the British and particularly of the products of the English public school system during the age of the British Empire. In those schools the ‘play up and play the game’ ethos was inculcated into the boys who went on to rule the Empire. That ‘do your duty and show no emotion’ attitude was expressed in Alfred, Lord Tennyson’s The Charge of the Light Brigade:

Theirs not to make reply,
Theirs not to reason why,
Theirs but to do and die:
Into the valley of Death
Rode the six hundred.

In more recent years the stiff upper lip has gone out of favour in the UK and British heroes have been able to show more emotion. Footballers now cry when they lose, and soldiers cry at comrades’ funerals, both of which would have been unthinkable before WWII.
Where did the ‘stiff upper lip’ originate? In 1963, P. G. Wodehouse published a novel called Stiff Upper Lip, Jeeves, and you can’t get much more English than that.
Strange then that a phrase so strongly associated with the UK should have originated in America. The first printed reference is in the Massachusetts Spy, June 1815:

“I kept a stiff upper lip, and bought [a] license to sell my goods.”

That citation doesn’t explicitly refer to keeping one’s emotions in check, but a slightly later one, from the Ohio newspaper The Huron Reflector, 1830, makes the meaning unambiguous:
“I acknowledge I felt somehow queer about the bows; but I kept a stiff upper lip, and when my turn came, and the Commodore of the Police axed [sic] me how I come to be in such company… I felt a little better.”
The expression can be found in several U.S. references from the early 19th century and was commonplace there by 1844, which is the date of the earliest example from a British source. (Phrases.org.uk)

Elementary, My Dear Watson – This famous line is the supposed explanation Sherlock Holmes gave to his assistant, Dr. Watson, when explaining deductions he had made.
In fact the line doesn’t appear in the Conan Doyle books, only later in Sherlock Holmes’ films.
He does come rather close at a few of points. Holmes says “Elementary” in ‘The Crooked Man’, and “It was very superficial, my dear Watson, I assure you” in ‘The Cardboard Box’. He also says “Exactly, my dear Watson, in three different stories.
The phrase was first used by P. G. Wodehouse, in Psmith Journalist, 1915. (Phrases.org.uk)

To Return to One’s Muttons – The source of this English phrase is the French, revenon á now muttons, which is found in the 6th Century play, Pierre Pathelin, written by the French poet, Pierre Blanchet. “Pathelin (often spelled ‘Patelin’) is a lawyer who has, through flattery, hoodwinked Joceaume, the local draper, into giving him six ells of cloth. While this injury is still rankling, Joceaume also discovers that his shepherd has stolen some of his sheep. He has the shepherd haled before the magistrate and there finds to his amazement that the shepherd has the rascally Pathelin as his lawyer. The draper, sputtering in indignation, tries to tell the magistrate about his loss of the sheep, but each time that he sees Pathelin he begins to rave about the cloth of which he has been defrauded. The judge begins to get somewhat confused, but tries to keep Joceaume to his charges against the shepherd: ‘Revenon á now moutons (Let us return to our sheep),’ he repeats time and again.” (A Hog on Ice & Other Curious Expressions by Charles Earle Funk ©1948)