Hey, not sure if this has been mentioned, but last night I watched the movie "Whip it" and it has a tickling scene in it, like 30 minutes into the movie. A group of kids comes into a diner and ask for a sandwhich called "The Squeal". The boyfriend of one of the girls orders it and says "I'll have the squeal, but not this squeal" and attacks his girlfriend's ribs causing her to, well, squeal. It seems like a genuine reaction to the tickling cause you see her try and grab his hands to make him stop and really jump away across the booth. Too bad it wasn't that chick from Juno or Drew Barrymore.