Thread Bomber 

Someone that spams the shit out of forum threads with posts

Timid: This guy Kelly is continuously posting on my thread!!

Artzy: I'm telling you he's a fucking thread bomber.

Thread Bomber by Professor Artzy January 11, 2017

Thread bomber 

An individual who constantly drops thread bombs in online forums or message boards that kill any future comments. Thread bombers may be clueless people who honestly think they are adding to the discussion or douchebags who intentionally ruin the thread.

That girl I added keeps posting the most awkward things on all my friends comments. I should unfriend that thread bomber.

Thread bomber by Cerberus66 August 12, 2010