Yes. Group sex with three other boys when we were all 12 or 13. One of the guys' moms had a copy of THE SENSUOUS MAN and THE SENSUOUS WOMAN and we read it aloud and practiced oral and anal sex on each other in the rec room above their garage.

I liked it very much at the time, particularly giving oral sex (the oldest guy was HUGE) and both giving and receiving anal sex, but I never repeated it after that and rarely return to those early experiences in my fantasies.