In poker, the term jam is another expression you can use instead of all in or shoving. It describes a player betting their entire stack.
For example, you could hear something as the cutoff opens for 2.5 blinds, the small blind calls, and I jam for 20 bigs.
This sentence means that the player from the big blind wagered their entire stack of 20 big blinds over the original raise and the call in front of them.
Broadly speaking, most poker players will use the term jam more often when there is action ahead of them. With no action in front, they’ll more often say something like, “I move all in for 20 big blinds.”