When you buy weed from a dealer and they just reach in a jar or something with their bare hands and hand it to you with no zip lock or anything. The marijuana gets sweaty from your skin.
"Fuck, Levi gave me 3 grams of sweatbud last night I had to walk around with it in my pocket for like 30 minutes not even a plastic bag, cheap ass."
Supervillian that steals everything they can get a hold of and breaks the rest, usually for lulz. A sweetbunny is classically found on irc networks high out of its mind on psychedelic drugs.