1 definition by Mr Chaz
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.
by Mr Chaz January 16, 2013