It's when a guy gets a boner during spooning with another guys, usually done by two straight guy who's quite close with each and they often spoon, so this is a non-gay activity :)
OMG dude! Did you just get a massive broner while we are spooning?
By JAYSONofabitch
When your bro gives you boner.
Dude I have a broner from looking at you.bro Boner
By peeing
A boner given by your best bro
"Yo man, last night my bro and I went at the club and we got high and drunk and in the process of almost fucking, I got a broner"
By cheettoloverfingers31
When a straight dude gets an erection around other straight dudes.
Dude#1: Dude, I got a total broner at last night ball game. Dude#2: Fag!
By ADD'EM
When a man lusts over another man's possessions.
Some guy had a broner when he was at the car show
By Bronerlover