1. (n) A boner that spontaneously erupts out of nowhere and from no sexual stimulation whatsoever. Usually occurs due to the G-forces present on roller coasters like Kingda Ka or Top Thrill Dragster.
Bros sitting on Kingda Ka about to go on the ride.
Bro 1: Dude, I'm so excited, this is going to rock!
Bro 2: Yeah man! Lets do this!
Bro 1: HNNNGH...! UGH...!
Bro 1: Bro, whats happening!
Bro 2: ... major rollerboner