Okay, so this wasn't on a plane, but it sticks out in my mind. My mom took me on a Greyhound bus from Chicago to Yuma, Arizona, and this one woman was totally whacko. She spent much of the trip sitting in the aisle conversing loudly with herself, and the driver never tried to get her back into a seat. Then she proceeded to lock herself in the restroom and stayed in there two hours! I can't remember how they finally got her out when desperate passengers started to complain. The final straw was when she got into someone's luggage at a rest stop and was busily putting on their clothes when we all got back on the bus. At that point, she was escorted away.

I did see a fellow passenger build a tent out of blankets and hide under it on ATA once, but that was the flight from hell (diverted, aborted landing, all sorts of horror), so I understood her feelings...I was ready to build my own tent and hide!