you go to a shady place and say

"hello I am x and I am looking for y" where y is illagle

some pepol in the room say "hello x here is some y"

you stay there

later a new person walks into the room says "hello I am z and I am looking for some y" you chime in with over pepol saying "hello z here is some y"

then a perosn in the corner who has not said anything takes down your names and pictures and sends them to the police who arrest you later