Rabbit hunting is an action of asking to see the remaining cards that would have been dealt on the board if the game continued, even though all players have folded and the hand ended.
While some casinos don’t allow dealers to do this, others let dealers accommodate this request at their discretion. Some online poker sites also allow you to go rabbit hunting and see what card would have come if you had continued in the hand.
For example, let’s say that you folded after the flop following a big donk bet from your opponent. As you had a promising hand and were curious, you decided to go “rabbit hunting” and ask the dealer to show which two cards would have been placed on the board on the turn and the river.