That would probably make the local postmaster VERY unhappy with you... And if you DID actually put any form of stinging insect in it, or possibly any insect PERIOD, I'm guessing you could end up with a bit of a court problem.
Perhaps, perhaps not. However, the court would mostly care about "intent": intent to do harm, or cause undue distress. It always pays to be exceptionally careful in this litigious era.
