I still laugh at that shit. Look them in the eyes, then run them up and down their disgusting body so they know what you are looking at, then put a disgusted smirk on your face and chuckle as you walk past them, arcing away slightly like they have rabies.  It never fails to get a stir out of them. From a mumble under their breath right up to a meltdown that would even make an ADHD kid look normal.