The following is from an interesting column in Salon written by an ariline pilot about flying titled Ask the pilot.

What is the most embarrassing thing you ever did as a pilot?

Well, this is something I once described in article for Airways magazine: While a crewmember one night aboard a cargo jet, I'd gone to the galley to get myself a Diet Coke. Clearing out the cooler, I mistook a block of dry ice for regular ice and threw it down the toilet. Now, to combine dry ice, which is frozen carbon dioxide, with any sort of liquid is to initiate a turbulent and rather unstoppable reaction, not unlike dumping water into boiling oil, or mixing vinegar with baking soda. Except, in this case, on a much, much grander scale than you can imagine.

After dispatching the block of CO2 I heard a deep and powerful burble, which seemed to emanate from somewhere in the bowels of the plane. It was similar to the sound your own innards might make if you've eaten an entire pizza or, perhaps, swallowed Drano.

When I turned and looked, the toilet had for all practical purposes disappeared, and where it once rested I now saw what can best be described as a vision. In place of the commode there roared a Technicolor volcano of bubbling blue toilet fluid thrusting waist-high into the air and, subsequently, all over my pants, shoes, and into every corner and crevice of the airplane's floor.

It took several minutes before the geyser of blue foam at last abated, and to this day the soles of my black Rockports are stained a lovely azure.