In poker, the expression bum hunting is used to describe a practice of chasing after bad players to join their table and try to play as many hands as possible against them.
The practice of bum hunting is much more present in online poker, although it sometimes happens in live games as well.
An example of this would be seeing a player you know isn’t very good (thanks to your notes, stats, and previous games) log in and join the game. You sit down at the same table as this player and start playing against them. After a while, the said player gets up and moves to a different table. You follow them to that new table and join the game once again, or get on the waiting list if there are no open seats available.
While bum hunting can be good for your bankroll, it is often frowned upon, as it can ruin the experience for recreational players and make them feel like they are hunted. This can cause them to play shorter sessions and ruin their desire to play in the first place.