My Little Pony: Friendship is Magic - Gabe Watches My Little Pony

Ponies are leaking EVERYWHERE!!!!

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@Chris:
From Urban Dictionary:

"A name typically given to the male viewers/fans (whether they are straight, gay, bisexual, etc.) of the My Little Pony show or franchise."

There you have it !
The term "Brony" may be more exclusive on more meme-savvy communities (KYM, Reddit, 4chan .. etc etc) but in general it means just that: A male (and/or adult) fan of the show.
By that definition, Gabe Newel is a brony.