First time with guys... me and 3 buddies, 3 of us were 16, one was 17... I hate perpetuating a bad stereotype, but we were all Boy Scouts and camping out as we were plotting a trail for an upcoming troop backpacking weekend.
Sleeping out around the fire one night, the 17 year old announces that he stole a bottle of JD from his dad's liquor cabinet, passed it around... didn't take too much for us all to get a little lit. Someone - i quite honestly forgot who - suggested we start playing "Truth or Dare"... but that seemed lame and we just got to daring each other to stuff. and naturally, the dares got more and more sexual.
Wasn't a huge leap to go from "I dare you to jack your dick for 30 seconds" to "I dare you to jack *my* dick for 30 seconds."
All of us wound up getting each other's cock and sack in our hands at least once... then the dares went oral... and all of us got a taste of the other 3's dicks and balls.
No assplay that night, but we did - eventually - end the night with 4 of us in a tight circle, each jacking the guy on our right until we all shot. 3 of us hit the abs and chests of the guy opposite us... the 17 year old, sadly, was more of a drooler than a shooter.
The combination of seeing my load across my buddy's body, a buddy's load shot on me, having a hand that wasn't mine getting me off, and the thrill of my hand making a cock that wasn't mine shoot... well it was enough to get me hooked on mansex for life.