basically, exactly what it is called. hugging a person while either you, or you and the other person is sweaty. its a good thing, considering most people consider sweat to be gross ( which I dont, unless its on a nasty, unhygenic person ) ..so if someone gives you a sweat hug, it means they like you, enough to get your sweat all over them. O.O yep.

(noun) A successful type of theft which results in an acceptable, impressive and rewarding payday for the protagonist.