Eat lots of beans and pickled eggs and beer the night before and FART. Then turn around and pick your nose and ask if they’d like some.
There are fart simulators. Fit one for easy use.
go scottish with a kilt (commando of course)
eat a bean diet combined with lots of olestral (that indigestable oil that seeps out at will)
and about the time their fingers get to your crack...let loose...