I make rookie mistakes all the time. The one that I'm most ashamed / amused by was 4 years ago when I wanted to empty my black tanks upon arrival. I didn't have enough in them so I decided to use the fresh water flush to fill them up before releasing the contents.
You guessed it. I became distracted and left the fresh water flush sprayer on while the tank filled and then over filled. I was outside when I heard dripping / leaking sounds coming from the coach and could smell the sewage. The neighbors were none too pleased and neither was my wife as we had to clean up the mess.