Get in touch with a chemical company, pose as a member of a search and rescue team and ask for a bottle of "Cadaverine". It's what's used to teach S&R dogs how to sniff out dead, decomposing bodies and reeks just like a corpse! Then get yourself a hypodermic syringe, stick it under their door and let 'er rip! They'll run like hell cuz the shit doesn't wash out and takes literally MONTHS to wear off... Is that evil enough for ya?
Oh wait, "Born Slippy" is cruel enough! (Shudder) Hey boy, what boy, look boy, hey boy, there boy, whoa boy, something else boy, boy oh boy I FUCKING HATE THAT SONG!