Broposterous 

When a "Bro" is being preposterous.

"These 'Bro' words are getting outta hand, it's kinda broposterous."

Broposterous by badgrammir August 17, 2012

proposterous 

a person who streaks down one's street with no shirt on

Look at that proposterous run by!! OH MY! She has no shirt!!

proposterous by Tommy234523456 May 13, 2007