Derived from the quote "In there like swimwear", this word refers to having sex, coitus, or intercourse with a woman. Women cannot say this unless referring to a guy having sex with a girl. "In there like swimwear" usually refers to when someone scores in some sports game. This is quite similar, but you score with girls.
George: Howd your date go last night?
George: Damn, you swam that wear dude?
Hayden: Hell Yeah! This is what I fucking live for!!!!!!!!!!