Corners in cribbage is a term which derives from the layout of the cribbage board. A traditional board is laid out in two rows of 30 holes for each players, and the winner is the first to 121 points - or twice around the board.
Consequently, when you reach the end of a row and start pegging up the next row, you have turned the "corner". Sometimes wagers or bonuses are placed on corners, won by the first player to reach that corner, although there is no additional score for corners in the standard cribbage rules. Some boards have extra markers for corners scored by each player.
The rows in between the corners are often called "streets", so a player with between 1 and 30 points is said to be "on First Street", and the home straight between 91 and 120 points is known as "Fourth Street'. The streets and corners are especially important in understanding positional strategy in cribbage.
(Thanks to Sam Van Wyck for this info.)
In cribbage, nobs is the name given to the Jack of the turn-up suit. That is, if the turn-up card is a four of Diamonds, then the player holding the Jack of Diamonds scores an extra point in her hand, known as "one for nobs" (sometimes "knobs") or "one for his nob" (or sometimes "his nibs"). This is a very old term, which probably dates back to the origins of cribbage. What is a nob? The word is British English slang for an important person, so perhaps this is why.
The nob Jack (or "right Jack" as it's also known, is essential for scoring a perfect 29 hand, and also affects discard strategy - you should try to avoid throwing a Jack to your opponent's crib if possible.
A flush in cribbage is 4 or more cards all of the same suit (for example, four diamonds). If you hold 4 cards of the same suit in your hand, you score 4. If the turn-up card is also the same suit, you score 5.
However, in the crib, only a 5-card flush will count (the 4 cards in the crib and the turn-up card must all be the same suit).
Renege in Cribbage is when you should play a card but do not. For example, if you say 'Go' when you could have played a card without going over 31. In Cribbage you must always play a card if you can, so reneging is against the rules.
The ACC Cribbage Rules state that (in ACC-sanctioned tournament play), a player may correct a "go" call before either player pegs a point or before the opponent plays a card. If this doesn't happen and the player subsequently plays a renege card, the opponent may claim a renege up to the time he or she plays the next card or announces the count of his or her hand.
When a renege is claimed, any cards played after the renege or "go" are returned to the players, and any points pegged (or scored) are cancelled. The player who was reneged against gets two points for each renege card: for example, if the count is 25 and a player holds A, 5, and 6 and does not play any of the three cards and says "go," that is a "triple renege," and the opponent gets six points (two for each card). See penalties in cribbage for details of other penalty points that can be scored in cribbage.
A skunk in cribbage is when one player wins with a margin of 31 points or more. Another way to say it is that if he makes 121 or more when his opponent has 90 or less, he skunks the oppoent, which counts as two games.
(Previous section: Cribbage rules - example hands)
The optional 'Muggins' rule allows your opponent to claim points which you fail to score in your own hand or play, or forget to peg on the board. While this certainly forces you to pay attention to the play and count your hand carefully, there are arguments against it: claiming a Muggin tends to slow down play, as you tend to count everything twice for fear of missing points. It also seems rather unfair to make you pay a double penalty (not only do you not get the points, your opponent gets them) for what is after all a simple mistake, not bad play. This is especially discouraging for beginners, who ironically are most likely to lose points this way. Muggins is usually played in tournaments, serious club play and between old friends who enjoy arguments.
By contrast, if you fail to play a card when you can, your opponent scores points for a renege.
(Previous section: Cribbage rules - the play)
The cribbage rules for scoring 'go' sometimes cause confusion. You earn a point for go when your opponent cannot go. This may be (a) because he has no cards (sometimes called 'One for last'), or (b) because he cannot play without going over 31 ('One for the go'). In either case if you make the total 31 you score only 2 points on the cribbage board, not 3 (because the go is included, as described above). However, you may well make 15 with the last card (in which case you do score 3).
An example sequence of play showing the rules for pegging points by both players:
Alice (pone) plays a 4, for a total of 4, and says 'Four.'
Bob plays a 7, for a total of 11, and says 'Eleven'.
Alice plays another 4, for a total of 15, and says 'Fifteen for two.' [and pegs 2 points]
Bob plays a Jack, for a total of 25, and says 'Twenty-five'.
Alice cannot go, as any of her remaining cards would take the total over 31. She says 'go'.
Bob plays a 5, for a total of 30, and says 'Thirty, and one for the go' [and pegs 1 point]
The count now goes back to zero, and the play continues. Since Bob played the last card, Alice goes first now.
Alice plays a 7, for a total of 7, and says 'Seven'.
Bob plays an 8, for a total of 15, and says 'Fifteen for two.' [and pegs 2 points]
Alice plays a 9, for a total of 24, and says 'Twenty-four for three'. [and pegs 3 points for her run of 7-8-9]
Bob cannot go, as he has run out of cards. He therefore says 'Go', and Alice pegs a point for the go. She also has run out of cards and so the game proceeds to the next phase.
Bob (pone) plays a 4, for a total of 4, and says 'Four.'
Alice plays another 4, for a total of 8, and says 'Eight for two.' [and pegs 2 points for the pair]
Bob plays a third 4, for a total of 12, and says 'Twelve for six.' [and pegs 6 points for the pair royal ]
Alice plays a 3, for a total of 15, and says 'Fifteen for two.' [and pegs 2 points]
Bob plays a 2, for a total of 17, and says 'Seventeen for three.' [and pegs 3 points for the run 4-3-2]
Alice plays a 5, for a total of 22, and says 'Twenty-two for four.' [and pegs 4 points for the run 5-4-3-2]]
Bob cannot go without going over 31, and so says 'Go'.
Alice plays a 9, for a total of 31, and says 'Thirty-one for two.' [and pegs 2 points. 'One for the go' is only scored when the scoring player does not make 31. ]
The count is now reset, and Bob plays first, as Alice played last.
Bob plays a Queen, for a total of 10, and says 'Ten.'
Alice cannot go, as she has run out of cards, and so says 'Go'. [ Bob pegs 1 point for the go. ]
For tips on how to make the most of the go, see the cribbage strategy section.
If you say 'Go' when you had a card you could legally play, this is a breach of the rules called a renege.
An optional rule that is sometimes played forbids a player from scoring a go when she is in the stinkhole (on 120 points). This is not part of the standard rules, however.
The stinkhole is the 120th hole on the cribbage board, one short of winning the game. It's so called because you really don't want to find yourself there!
A commonly-used optional rule has it that if you're in the stinkhole, you can't peg out on a Jack (two for his heels) or a go. Sometimes this also applies if you need 5 or fewer points to win. While this is not part of the standard Cribbage rules, you are free to use this rule so long as all players agree on it beforehand.
The official ACC cribbage tournament rules specifically say that this score still counts even if the dealer would peg out and win the game as a result:
Rule 6.3. Scoring When The Starter Card Is a Jack (His Heels)
a. When a Jack is turned up, the dealer is entitled to two points.
b. The dealer may peg out into the game hole by turning a Jack starter card.