The act of patrons staking out and claiming a table in a "seat yourself" lounge/restaurant before staff is given a fair chance to buss it off or previous customers leave. This usually happens during a dinner-rush.
This results in the server becoming annoyed and having to awkwardly reach over and make "small talk" with customers as they wipe off the previous mess.
Server 1: " My table is just about to leave, they're getting their coats on. I just have to ring-up a Mastercard, and I can clear it off..."
Server 2: "Too late. Check out the dude at the entrance. Definitely table poaching. He's making a bee-line to 106. Aaaaand, yup, he just asked your table if he could sit there."