A group of guys that haven't seen each other in awhile getting a little extra bromantic with each other.
The guys trip to Vegas turned into a total bro-union as they hadn't all seen each other in years and had been drinking steadily for 12 hours.
by HeyCoooooooory April 06, 2010
1 more definition
The reunion of bros after a LOONNGG time.
bros Mario and Luigi had a brounion after being apart a shit long time, and partied their asses off.
by cfrk12 June 11, 2012