1. A term stemming from the TV show "My Little Pony: Friendship is magic" in which one of the characters, a pegasus named Rainbow Dash, has her wings shoot up involuntarily when excited.
2. Any involuntary physical indication of excitement, especially sexual excitement.
That dancer gave me a wingboner, I hope nobody saw.
Derived from the show "My Little Pony: Friendship is Magic," a wingboner refers to a pegasus experiencing an involuntary flaring of his/her wings upon arousal. In the episode "Over a Barrel" the pegasus Rainbow Dash may have experienced this. She had closed wings until one other pony, named Pinkie Pie, appeared in a prostitute outfit. Dash's wings were flared (and she bore a very interesting look on her face) for the duration of the song and dance routine. Her wings returned to her sides upon the end of the dance.
Even the mildest thing can give an adolecent pegasus a wingboner.