Have you ever been interested in becoming a pony? Well, I think right now, this is about the closest you can come. An interesting thread/guide on /mlp/ was given to me, explaining how you can hypnotize yourself into thinking you're a pony. And, of course, this can work sexually as well.
If you want to give it a shot, check out the google document here. And heck, if it works, tell us so in the comments! I've never tried hypnosis before, but it seems pretty interesting.