When someone that has stayed at your home really wants to shower, but doesn't feel like making their way back home yet. So instead they decide to use a sink in your house just to wash their hair, so they can continue doing social things without having to look like a scumbag
Can also be preformed at your own home by yourself when you're either:
A. Straight up lazy
B. In a rush
Man.. I really want to shower but I'm too hungover to walk back to my house right now. Is it cool if I do some Shower-sinking in your kitchen?