To draw cards that make a hand that is different from the hand you were originally trying to make.
Usage: You back into a hand when you are intentionally in the pot to make a different hand than the one you ended up with. For example, if you flop a straight and up with a flush, you would say "I backed into a flush."

Making a hand other than the one intended. Example: Having J/10 of Clubs with a flop of A of Clubs, 5 of Clubs. 6 of Spades. The turn and river are K & Q of Hearts. You made a straight instead of the intended (and more likely) flush.

When you have three cards that would support a straight, but you need the turn and river to make a straight.
Usage: Like in sentence "He's likely got 6 outs and a backdoor straight possibility."

A re-raise from a player who originally called.
Usage: Usually permitted only in home games, in which the rule that a raise must equal in size the previous bet or raise does not hold. Like in sentence "An oft-used ploy by many players is to backraise with small pairs."

A bad beat jackpot is offered by a poker room when a very good hand loses to an even better one.
Usage: For example:

Player 1 holds AA Player 2 holds KK

The community cards are: AAKKQ

Player 2 would have four of a kind, Kings but still lose to Player 1 who holds four of a kind, Aces.

This is usually enough to trigger a bad beat jackpot for the hand. Normally the losing player in this hand would be awarded 50% of the jackpot fund, the winner gets 25% and other players who took part in the hand get the remaining 25%. Different poker rooms offer different levels of payouts for bad beat jackpots and have different losing hand requirements, for example, Party Poker bad beat jackpot winners must lose with a hand of four 8s or better to qualify.

Short for a Full Barn which is slang for a Full House.
Usage: Like in sentence "Between two barns, the one with the higher ranking set of trips wins". Used very rarely.

A $6 bet made with a red $5 chip and a white $1 chip, named after the color of horses.
Usage: Such a bet would be made in a $3-$6 limit game. Bay comes from horseracing, where it is a reddish brown horse with black markings; red casino chips often have black markings on their edges.