When you are so intensely afraid of another individual that you reach a point of sexual arousal. The fear boner is a sign of submission to a more powerful individual.
I hope Professor Tony Yueng didn't see my fear boner in class today.
by Tod Jenkins September 15, 2010
Sexual arousal brought on by the excitement and/or anticipation of something that would otherwise be terrifying to a normal person.
Watching the trailer for ‘IT 2’ gave me a raging Fear Boner.
by Dean Wilton May 11, 2019
An unexpected boner provoked by a frightening experience or unusually strong or dangerous potential mate.
Sally: I'll break your fucking nose, Tom.
Tom: Fear boner, activate!
by jpb103 May 4, 2016