Something to do after you have been hypnotized. Like, after you've been hypnotized and are wondering what to do next, only you can't think exactly what it will be so you don't know what you will do but everyone else in the room knows already and that pisses you off, them knowing and you don't, so you rip off your shirt and skirt and say -- all right I don't think I was hypnotized anyway. Probably part of the hypnosis was to tell you to forget the posthypnotic suggestion, and forget that you have been hypnotized. At least forget it for a while.
Like at that party last Saturday night when I volunteered to be hypnotized and they gave me a posthypnotic sugestion -- but I forgot about it till just a few minutes ago. Before we started I was convinced that a posthypnotic suggestion would not work on me.