Sometimes used to describe an internet forum thread where forum members all give each other kudos (Or rep where a rep system is present) for some non-event that has occurred.
Group intellectual masturbation.
guiz I writ a poem, post urs 2!!!!!!oneoneoneleven
Jerker2-Oh d00dbro ur peom is zo gud read mine itz ded deep <3
Jerker3-Wow ur peotri iz so gud we R all so much deeper that every1 else on deez forumz ^__^
Forum user-Wow what a fucking circlejerk, stop spamming and go get laid you fucking losers.