A form of Sexual Asphyxiation you go down on your partner (
Head) while they stand in the shower and
water runs along his or her penis and
water (Boarding) you while you pleasure him or her.
"You pair are always at it! I didn't mean to walk in on you
head boarding her last night"
"I heard you and your
boyfriend in the shower last night."...." Yeah, I totally
head boarded him, but he loved it".