1 definition by NigelMarsflap

Top Definition
When look at the penis externally, the flap of mars is where the scrotum curls around the side of the shaft, leaving a flap which doesn't move without prodding or poking.
Man 1: I've got a big dick.

Man 2: Yeah, but The Flap of Mars in your pants is below average in terms of flaccidity.

Man 1: ...damn.
by NigelMarsflap June 04, 2010

Free Daily Email

Type your email address below to get our free Urban Word of the Day every morning!

Emails are sent from daily@urbandictionary.com. We'll never spam you.