A man who's penis is equal or smaller than one of a mouse. Usually people with the name "Markus" have a Mouse Dick.
"What's up mouse dick?"
"What happens in Vegas, stays in Vegas; except mouse dick, that's for life!"
"What happens in Vegas, stays in Vegas; except mouse dick, that's for life!"
by Dicktionary1020 January 7, 2015
A golf term; meaning you short a putt so bad you have moused dicked said putt. Good luck next time fool.
by Austin Ryan July 16, 2015