Circle Jerk (Sexual)
A circle jerk is a term that originally seemed to apply most to men (actually often boys, as it seems to involve high school students rather than more mature people). A couple of men stand in a circle, all facing each other and masturbate. In some cases, a circle jerk is done not by masturbating yourself, but by masturbating the person next to you.
This is often a game played by sexually curious younger males, and variations of this act may bring it closer to being not so much masturbation as a gentle gay or bisexual sex act. There are competitive versions that the winner is first to cum or last to blow, and in others a target is placed in the middle, often a cookie or cracker, and the loser has to eat the cookie covered in cum. It is rumored the the rap-rock group Limp Bizkit got their name from this sort of activity.
* Urban Dictionary - People's defintitions of circle jerk.
In the world of TGP and MGP sites, a circle jerk is a site that appears to be a real TGP, but has either few or no actual linked galleries. This sort of site is created with the goal of getting many people to visit and to make their hit stats look really good. The underlying goal of a circle jerk site, especially when linking to other circle jerk sites, is to get the average visitor so frustrated because they can't find free porn as to actually buy a membership to a site to get the porn they want.
This is a pretty poor sales technique, but apparently must work because there are any number of circle jerk sites out there.
Circle Jerks (The band)
Finally, I cannot allow the section to exist without a link to one of the seminal punk rock bands, The Circle Jerks. As I write this, they are on tour, maybe 25 plus years after the started out. That is something!
* The Circle Jerks - Official site for seminal punk band the circle jerks