(noun) an empty cigarette pack that is intentionally kept (not crushed or thrown away) so when someone tries to bum a cigarette it can be used to justify not giving them one.
guy1: what a party last night! man you got any cigarettes?
guy2: I'm all out. (gestures to decoy pack on coffee table.)
guy1: I guess I'll have to go get more then.
guy2: see ya.
(guy2 pulls fresh pack from pocket and lights one up.)