The cricket stuff would be annoying to deal with in the aftermath, but damn is it a good and easy idea.
The worst prank I ever played on someone was the day I found a bat hanging on the T-REC fence. I took my hat and scooped him up in it. I turned it loose in my buddy's bathroom at Gibbs. I thought he would fly around but he latched on the vent in there and didn't start moving until late at night. I got a phone call around 1 am telling me what a [penis] I am.
When I was coaching HS in Alabama we would take our players to Marion, AL. for football camp. Its in south AL. and one of the hottest places I've ever been too. We would sneak in the players rooms at night and put sardines in the helmets and shoes. I super glued one coaches flip-flops to the floor. And to the same coach I put approx. 500 crickets in his room. I even put a small snapping turtle in one coaches bed. We would go over to coaches houses when they weren't there in the fall and sow the yard with rye grass so it would grow and they would have to cut it or sometimes spell out words. Fun Times!
I put about a 40 lb live snapping turtle in the floorboard of a guy's truck. It was very hard getting that big bastard out of the truck.