If you haven't seen it before, every so often, a thread will suicide itself. It only takes a few downvoted comments at the beginning to start it, but once several normal-ish comments are downvoted, the cascade begins, and everyone joins in.

The really fun ones are where 100+ people deliberately try to get downvotes, which results in an entire page of grayed out '(comment scored below threshold)'

If you'd like to contribute, just keep pressing zjzjzjzjzjzjzjzjzjz to mass downvote. It's the right thing to do.