The act of "replying to all" on an email chain just to specifically thank one individual. While usually well intentioned (and intentional), the practice often becomes an annoyance to everyone involved.
Person 1: "Did you see that Nicole just groupthanked Brian on an email chain with 120 people?"
Person 2: "Well, at least it's better than what she mistakenly replied to the entire staff after the 2007 Christmas party!"
Group work that results in no progress being achieved due to internal conflict and strife. End conditions are either equal to or worse off from those at the start.
The group failed to achieve anything due to all the groupsink going on. People were more concerned about being better than everyone else than actually doing work and sabotaged so many other people they also sabotaged their own work.
Groupwanking is a term when a group of men gather around a cookie or biscuit and start masturbating on it. Last one to ejaculate needs to eat the biscuit.
First person to ejaculate: Thank God I ejaculated first, Phewwwwwww
Last person to ejaculate: Fuck you man
Others: EAT IT, EAT IT, RULES OF GROUPWANK
"Hey Dan Coolings, feel like coming back to my place for a groupshank? Furgus Turnburger's in if you are lol!"
"Yeah NP, Gotta love a good groupshank, i had one the other day with Sidney Dickland and Rupert Pond, but he was in a shit bad mood, gettin up in my grizzle biscuits. Heck! It turned in to a God Damn gang Bang!!"