The Flap of Mars 

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.

The Flap of Mars by NigelMarsflap June 4, 2010

fast flap 

That piece of extra skin that hangs down from a domestic or wild cat's belly. Some say it is to help the cat run faster. This loose flap of skin on the abdomen helps the cat stretch out further with each stride. Some say it is extra skin in case the cat has to binge eat and store extra fat in the wild.

The bengal's fast flap helps it run faster, up to 30 miles per hour.

fast flap by Rosie v B September 14, 2013

Bird Flap 

A dance typically conducted while pre-gaming before the bar.

"I feel like tonight's gona be a great night downtown, Ryan is already drunk and doing the bird flap!"

Bird Flap by MadPlayRK July 6, 2014

Knacker Flap 

A Knacker Flap is the large flap of skin prevailing from the gut that hangs over a males genitals, making them completely invisible when naked. The sighting of a Knacker Flap usually occurs in older obese men, and is usually tucked into their shirt. It is the male version of the "gunt" which is that of a female Knacker Flap.

Holy shit, that dude's got a mean Knacker Flap!

Omg is that guy naked? Where's his privates? Oh they're underneath his Knacker Flap.

Knacker Flap by purplejane September 8, 2014

muffin flap 

the burnt flap hanging off the side of a stale muffin; often used as an insult to people who are hella crusty

guy 1: dude that girl is sooo hot
guy 2: yeah but she's crusty AF
guy 1: dang it
guy 2: I hate it when girls turn out to be muffin flaps

muffin flap by lizmaster March 12, 2015

dolphin flap 

when a vagina moves like a dolphin

Jesus Sally, you got a Dolphin Flap

dolphin flap by lol memes m8 69 August 30, 2015

time fapsule

When one places their favorite and most cherished pornographic content into a time capsule, buries it and 10 years later digs it up and masturbates to it again.

"Dude do you remember that time fapsule I made in 8th grade?"
"Yeah."
"My dog Rocko just dug it up, I guess there's no point in waiting now."

time fapsule by Saltslinger August 12, 2016