Similar to the Pirate Bath, a Slut Bath is performed by people who smell quite rank but simply do not have the time for a full bath, like a prostitute.
The person in question takes a wet wash rag or wad of napkins, sometimes soaps them slightly, then washes the under arms, neck and private areas vigorously.
Amy: "I have an interview in 15 minutes and I smell like crap!"
Sheila: "Don't worry, run to the bathroom and take you a Slut Bath. You'll be fine."
When a girl generally wearing a tube top or even one of your friends who happens to look expecially slutty any given day appears to have taken a bath in "slut." On occastion a slut bath might not appear to have taken a bath in slut until you see her hitting on every boy at the party including your boyfriend.
"Get off my man, you slut bath."
"Wo, you had a slut bath didn't you?"
Person A: That girl looks insanely slutty.
Person B: Someone took a long slut bath.