There's all sorts of slang used in forums.
Posting something spurious in order to "bump" a thread is normally frowned upon.
"Necroposting" refers to a making new post in a very old thread that brings it back from the grave - in some forums this is considered bad form, but here people prefer you to bump an old thread rather than opening a new one on the same subject (assuming you need to ask something new once you've read that old post!)