A decoy posing as a boy or girl would entice the man into engaging in a sexual act noting that he or she is a minor. The man would turn up at the location given by the minor and the FBI with their Party van and Chris Hansen would be waiting there.
The most notable and hilarious arrest was a sick guy who walked into the house naked wanting a 14 year old girl to 'perform sexual acts' with a cat and then 'fuck her afterwards' with the aid of cool whip.
Gary: "Woah, really!?" "How old was the girl?"
Gary: "Pedobear much, did he get Party Van'd?"
Barry: "Yep, he is in court next week."