Have pie eating contest with at least 4 people. The contestants will have to eat the pies blind folded.
So the prank is all the pies will be normal except for one. The trick pie will look normal but inside there is going to be bugs at the bottom(roaches or something).
So when it starts they will think they are eating a normal pie and when they start tasting the bugs tell them "The pie is fulled with nuts that's why its crunchy".