BCWW is an acronym for "Bow Chicka Wow Wow." It can be used to describe the act of sex, but is also sometimes used as a form of the bases, B for first base, BC for second, BCW for third, and BCWW for a "home run."
-Yeah, I "BCed" with him last night.
-You guys have been dating for two months! When are you going to BCWW?