Confession: when I was brand new to PoA, about 4 years ago, I threw a personal insult at someone.
I still remember the thread. It was titled "don't be That Guy" and was about someone arriving at an airfield in a manner the OP disapproved of. I am firmly opposed to disapproval, so I voiced my opinion that the OP was being overly snooty and perhaps HE was That Guy. To punctuate my argument, I finished with "I'll bet you wear epaulettes." I thought that was quite clever at the time.
Two things happened. First, the OP blocked me. Second, the mods put me in the time-out chair for a week.
I learned my lesson. Mostly.