Similar to clog; can be used to describe disgusting things like Disney's the Santa Clause
They clugged Tim Allen to Santa.
The engaging of sexual intercourse (anal or vaginal) from behind.
In the context of online gaming "clug" is synonymous with rape, pwn, skull fuck, and other terms that declare superiority over other gamers.
Jared's mom can take a pretty hard clugging.
When two people, be they related or otherwise, attempt to hug but instead knock their heads together, in extreme cases, female victims of the clug yell loudly further embarrasing any male clugger.
*high pitched scream*
Guy 1: what was that?
Guy 2: haha! Joe and Maria just clugged!
Guy 1: nice one! lets go give him a hard time.