Since I don't see any posts in this topic yet, I'll start.
I'd like to nominate the moron who was parked in front of us on the car ferry from Wales to Ireland last week. In spite of multiple announcements urging otherwise, this goon hopped in his car, in the closed up hold of the ferry, and started up his engine, treating us all to 10 minutes of carbon monoxide therapy. Possibly next time he will do us all a favor and repeat the mistake in his own closed garage.