Maybe with a little transmitter than can activate a remote speaker placed nearby? Like one that shouts "Hey!" from behind the hapless victim?
Much as I'd like one that throws pies, I'm morally unable to waste food like that. Well, unable to waste pie like that.
Got invited to a birthday party and to "Bring a Pie." So I got a good Marie Callendars Banana Creme Pie - the eating kind, not the splutting kind. Brought a big ice chest and kept it chilled all day in the car.
Little did I know... "I demand you hit me with it!" "NO - You should have mentioned that before."
Making a gag pie is easy, just ask Soupy Sales, he went through hundreds. Wrecking a really good pie is hard. I'm gonna hate myself if I do it... I dood it.