I've had one in my life, and it was definitely not due to not wanking. I was probably about 19, so I was masturbating, oh, five to ten times a week.
The wet dream felt really good, because I woke up right in the middle of my orgasm. It was like, wow, I got a free orgasm! (And I didn't have to do a thing except lie there and sleep.) I like girls, always have, but the weird thing is that in my dream, I was doing a dude in the butt.
As far as the extent of my gayness goes, when my male cousin and I were teens, we'd mostly just jerk off together. But both of us being virgins, we wondered, "what does pussy feel like?" We figured it might be a little like a butt hole, so we decided to try on each other. I let my cousin do me in the butt on a few different occasions, but I never got mine into him. My cock was too big. (I was just plain huge compared to him. We haven't masturbated together in years, but I'm sure I still am, based on a conversation I had with one of his crazy ex-girlfriends, where she described him as "not very well built down there." I had to bite my tongue not to say, "yeah, I know.")
I wish I had wet dreams regularly, no matter who I'm doing in my dream, male or female. Once in a lifetime is not enough.