We just found out what "Bronies" are, and we were pretty shocked when we realized it wasn't a joke.
"Bronies" are adult males who have an obsession with My Little Pony. We're talking merchandise, clothing, the show itself, the magic of friendship the show promotes, and everything else. Also, we know what you're thinking. But supposedly, most bronies are pretty adamant that they are "definitely not perverts or anything," so we're glad we could get all that out of the way right off the bat.
Someone even made a documentary about them. Check it out here: https://en.wikipedia.org/wiki/Bronies:_The_Extremely_Unexpected_Adult_Fans_of_My_Little_Pony
Here's a photo taken from WhatIsABrony.com: