The act of having sexual intercourse with a woman while she is having her period with the intention to help her "clean her pipe".
1. Dude, it's that time of the month -- pipe cleaning time!!!
2. Dude 1: Yo, my woman's on the rag,
Dude 2: It's cool man, you can totally pipe clean that.
3. Ya don't need lubrication when you're pipecleanin'!