Pulled a Dennis is when you let all of your emotions building up until you finally cant hold it in any longer and you explode like a volcano and finally let everything out from the smallest of things to the biggest of things and finally get relief you needed and are clam and relaxed until it happens again.
This is what we call pulled Dennis.
You blow up on a coworker because they keep moving your chair all over the office and its never in your spot when you come in in the morning and you finally pop because you have finally had enough of it. So you pulled a Dennis.