A futon in the apartment (usually studio) of a loser who has no girlfriend and is always masturbating.
Kristen: Whew, I thought I might get pregnant the other night.
Jacinda: Why, what happened?
Kristen: I sat on Santosh's cum-stained futon when I visited him.
Jacinda: Why, what happened?
Kristen: I sat on Santosh's cum-stained futon when I visited him.
by SantoshGeorge September 25, 2008
A cum-stained futon (or CSF) is what you find in the home of a low-class loser who is always at home beating off on his futon. It is stained with his semen (cum) drops.
Jane: Did you visit Peter's apartment?
Mary: Yes I did. He had a cum-stained futon in there.
Jane: Yuck!
Mary: Yes I did. He had a cum-stained futon in there.
Jane: Yuck!
by SantoshGeorge March 10, 2008