The day I went to Cleveland, I decided to take public transit to the airport. I got on Caltrain and sat at the back of a car, which has a ramp leading up a few inches between cars.
I fumbled as I got up at the Millbrae stop after I set down my luggage (which had been on my lap), giving my Tumi Vapor a nice ramp to ride on. It got some nice momentum and whooshed down the aisle, perfectly centered.
Worse, it was aimed directly at a woman waiting to get off the train. Oh no!
I was mortified. I was also laughing.
Fortunately, it came to a stop right as it got to the woman, and she was very graceful about my abject and embarrassed apologies.
Pretty much everyone on the train had a good chuckle over it.
Unintentional luggage acceleration is one of the potential downsides of four-wheel luggage, but in this case, it all turned out all right.