Here's a harmless* prank - based on the recipe for Treacle Spice Cookies.

Instead of forming the dough into flat cookies, you just roll it up and twist it into little spirals, then bake them and use them in whatever fun way you like - leave one on your boss's desk

Or gross out your friends by pretending to pick one up off the path, then eating it ...

*Harmless, unless your boss fires you for mucking about, that is