Usually takes place after a heavy night of drinking. This is where the female will stop at nothing and is desperate to have sex. Completely neglecting the fact that you may have whiskey dick
, she vigorous "mashes" her vagina into your penis in hopes of stimulating a flaccid erection
"Man, Dana was mashing potatoes all night long"
The act of stuffing a potato into a woman's vagina and having sex with her until it is mashed. Eating the potatoes is then optional.
I was mashing potatoes with your mom last night.
A euphemism for masturbation
"John, what have you been doing your forearms are massive?"
"Oh you know just mashing potatoes"