The act of wasing one's hair (on one's noggin), and applying the leftover shampoos to one's pubic hair. May sometimes be carried out for masturbational purpose rather than for hygienic one. Believed to be carried out often by a Jacob, and possibly by a Thomas.
When you wash your hair (with shampoo) and the shampoo has gone down your body and gathered up in your pubic hair. Sometimes you will notice when you have gotten out of the shower, meaning you have to get back in to rinse your pubes.
(from outside the bathroom)
"Why've you turned the shower back on?"