An erection inspired by the actions of your buddy- be they sexual or just plain impressive.

A broner is a form of a male erection (commonly referred to as a boner) but this variation is when the male erection occurs because of attraction to another male or in this case "bro" forming the name broner.

An unintentional boner from your guy friend.

When you get a really good feeling by thinking of, or hanging out with, one of your bros.
Like "Lady Boner" it does not have to have anything an actual erection.
It is usually completely non-sexual.

An unintentional man-inspired boner

Erection gained from looking at the bread emoji

Next Level Bromance, but can be with more than two bros
Constant communication between each-other everyday

Drunk festivities include show public display of affection & grabbing balls
During conversation, they speak their own language (i.e. inside jokes)
Together they are inseparable