Being asexual, I don't really have any fetishes to speak of.
However, not wanting to make a post without contributing something to the conversation, I did have this one friend of a friend that did something... strange during Bio class. According to my friend, they were watching a documentary on bonobos in class. For those who don't know, bonobos are very, VERY horny, as in they have sex about 50 times per day. At one point, two females started to have intercourse, and his jaw apparently dropped and stood transfixed.
So yeah, a fetish for two female bonobos doing it. Not two male bonobos though, that would just be gay.
I... I think I need to go wash out my brain.