Have said this before, but I used to meet with a former Marine, and now firefighter for a major US county, who wanted nothing more (often begged) than to give me head and bottom for me. And once, it was after he put on a show with a chick for me like a pro. If anybody denies bisexuality exists, have them come talk to me.
The area around the butt is very sensitive (no surprise) and once a dude gets past the stigma, it can be a great thing!