guilt shower

(n) When someone is so ashamed of somthing they did (usually the night before) that their guilt feels like physical dirtiness, leading them to take a long, thorough shower. Generally follows a walk of shame or one night stand.

The process of showering after having sex with or messing around with someone you later regret. it is often done more than once, and can be a sort of therapy. it is a psychological way of removing all traces of those people you regret being with, by "washing them off."