Washin the undercarriage 

The quick shower that a man or woman will take prior to a scheduled bang session. This may be needed to remove dingleberries from the ass, or worse odors from the tuna casserole. Washin the undercarriage is needed but yet also a waste of time since all you're going to do is shoot a load in that twat.

"Before we have have sex tonight, I'm going to be washin the undercarriage since I just worked out at the gym." Said Sarah to her hot, huge dicked husband.

Washin the undercarriage by Mr Chaz January 15, 2013

pressure washing the undercarriage

to use the shower massager to wash your taint and or buttocks without the need for a hand towel.

After going to Burning Man for a week and only having access to Wet Wipes and porta potties with single-ply toilet paper, my first shower was amazing. I was pressure washing the undercarriage for a few minutes before I stopped feeling like a primate.

pressure washing the undercarriage by partytrap October 12, 2010