it would cause most guys excruciating embarrassment. We don't share such behavior: even our chatter is infinitely less intimate than girls'. You ladies are more in touch with your sexuality, and therefore more likely to talk frankly about it.
One exception to the circle-jerk rule: post-feminist writers (Paglia et al) have noted the incidence of crypto-homosexual behavior among spoiled frat-boy types. "Dragging train" (no, you don't want to know) and other quasi-rape rituals are, she says, a type of transference. Unable to copulate with each other because of taboos, they use a female as a proxy object-of-desire.
As we know for sure that this goes on among the Greek-letter crowd, we can well imagine that the more openly gay in their number might also do something like a circle-jerk as a bonding/mating ritual. A recovering frat-boy out there will no doubt confirm this...
No, I don't think it happens often... there are "jerk parties" that get arranged at people's houses for that purpose, but it isn't like guys growing up have a sleepover and do a circle jerk. It isn't that unusual for guys to mutually masturbate each other, or at least watch each other, but I don't think you'll find more than a couple of guys who will do that type of experimentation as kids... and you'd need more for a "circle"! Guys can be pretty homophobic.
I know a few of my old high school friends have played Soggy Biscuit, which is pretty much a circle jerk. And there was this camp thing that some people go to where people used to jizz a lot for jokes. Like some guy fell asleep and they squirted jissoms in his mouth, or they all jerked into a bag and filled someones bed for it. Its a certain type of person, I dunno. Its weird, to me.
Me and some friends did experiment, during highschool. A lot. But it was never more than 3 guys.