O/T - A label on forums that means a thread is going off the rails

A label on forums that means a thread is going off the rails and no one cares anymore.

User123: This thread is O/T and I’m gonna kick all of you out.

Thread: Discussion about cats. Comment: O/T: Why is this still going?

DM: Hey bro, that thread is O/T and I’m done with your nonsense.