Twist is poker jargon for a round with specific rules which is sometimes used in the poker variant stud poker.
One can replace any round of (or add a round to) a stud poker game with a twist round, in which each player is offered the option to replace exactly one card in [...]

garbage

The “muck”.
A worthless hand.

going south
To sneak a portion of your chips from the table while the game is underway. Normally prohibited in public card rooms.

grinder
A player who earns a living by making small profits over a long period of consistent, conservative play.

guts, guts to open

A game with [...]

equity
One’s mathematical expected value from the current deal, calculated by multiplying the amount of money in the pot by one’s probability of winning. For example, if the pot currently contains $100, and you estimate that you have a one in four chance of winning it, then your equity in the pot [...]