Verb. Intransitive. To masturbate, exclusively used when referring to a female. Some say it is actually a lesbian sex act, but they are wrong. That's called scissor sisters.
Mike : Did you hang out with Fugu yesterday?
Matt : Nah, man. I couldn't get her out of the fucking house. She was slamming the clam for like five hours!
Mike : Damn, man, she's gotta be chafed after that.