Bump aka BTT = Back to Top. Someone is returning the thread to the top of the forum.
IIRC = If I Recall Correctly.
If your a team member you have a "My Active Topics" folder. Non team members do not have one. When you post in a thread you are "tagging" it. To find the thread again you just look in your active topics folder.
COC = Code of Conduct.
IBTL = In Before the Lock. Someone has violated the COC.
I'm sure the other guys will post the rest.