Two people on a forum who always post after each other. This is either intentional because they're so dependent on each other they can't think for themselves, or it's by coincidence since they're always active on the forum. Sometimes other forum members think it's cute if the two are likeable, but most of the time it becomes annoying, especially if they post about things no one else cares about or they're part of a forum clique and bully other members.
"Why are those two always posting after each other all the time?"
"They're the forum's posting pals. They used to be funny but now no one can stand them."