ahh, I rember that old time I wanted to make a "your mom bot" for discord, one of the function was saying "No, your mom" when someone said in a phrase "your mom", little did I know that discord bots read their own messages if you don't check it
I broke my brother's exchange beta 4 install by telnetting into SMTP port and sending an email with an accidentally typo'd recipient. The bounce bounced, that bounce bounced and it continued until priv.edb was full and the service crashed. After a morning on the phone with Microsoft support he asked me if I did it. They made a hotfix for the bug.