Ass Flex

Someone that is an uptight douchebag who lifts a lot of weights and thinks they are tough shit.

That guy just bumped into 60 year old lady cause she was in his way, what an Ass Flex!

Ass Flex by Slobo March 12, 2008

ass master flex

one who is a master at flex ones ass muscles!

How you doing ass master flex
yo dude im flexin ma arse yo!
shizzle ma nizzle ass master

ass master flex by amander March 30, 2005

assflex 

When your jeans are so tight, it makes it look like you are making your ass flex. Most commonly happens when you are wearing skinny jeans.

Person 1: Oops I dropped something.
(Bends over to pick it up.)
Person 2: Nasty! What are you trying to do an assflex?
Person 1: No!

assflex by googoogoodolls January 7, 2011