Something I've never really had the opportunity to try (and succeed), it's getting a fist in the butt.
Now again, not something that really dictates why it should be hot, it's just one of those fetishes that is awesome based on it's pure absurdity. And additionally, it's even more awesome because with this comes bragging rights (at least for the perverse).
Like I said, this has never been successfully been pulled off in my personal experience, but what I know, there are a few tips for a successful "fist pump" (hah...see what I did there?):
1) Pick a chick (or dude if you prefer) with small hands.
2) Position is everything. As seen in the picture (which I, in no right, claim the rights to), the position he's in allows for more "stretching". It's usually advisable for any type of penetration to begin on your side, but on your back is the next best position.
3) Lube. Lube. Lube. You are obviously not going to pull off this expert position without unholy amounts of lube. The recommendation here is to use some type of numbing lube to start. This type of lube contains lydocaine, which as you know, has a strong numbing agent. Recommend a decent amount both on the outside as well as on the inside. Then, once the numbing has taken effect (don't worry, it doesn't feel like a dentist office numbing), then use plenty o' water based lubricant.
4) Gloves! While bare skin might be okay, it's waaaay better to begin with some type of non-porous hand covering. Latex gloves are always the best kind (not like...doctor gloves, like actual latex gloves). If latex isn't an option, then possibly vinyl gloves.
5) Practice first. With any rule involving butt play, you never go right to the big stuff. You can, but, well, you're going to be in ALOT of pain first. Start small, and work your way up.
If done right, this can be really hot. Why you ask? Because being violated by anyone (especially hot chicks, and especially especially the chick in the pic) like this is just awesome.
