Using a cheap beer, preferably a Miller product or Old Style (if you have no respect for the woman feel free to use Milwaukee's Best), is the best way to give a woman an authentic Milwaukee Power Wash.
During sexual intercourse grab a bottle or can of beer and shake vigorously while bringing your woman toward climax. As she's close to orgasm pop the beer open and aim the stream at her clitoris. This will enhance her experience and potentially bring a would-be one night stand back for more.
Contrary to the name of the move, it originated in the Chicago-land area, and the beer of choice was commonly Old Style which is brewed in Milwaukee.
Lyle: I took this chick home last night and gave her a Milwaukee Power Wash.
Bob-ay: How'd that go?
Lyle: Really well! I executed it perfectly and she's been calling me her God.