I had this story from the "normal-sized" person involved(*). To my knowledge, both people have left that company anyway, although I did know the one guy and saw the other.
Imagine a guy so grossly obese that he didn't stand in front of the urinal, he sort of "docked" with the urinal. Imagine him and Mr. Normal attending some sort of corporate meeting or user group across the country. Mr. Normal spent the first leg of the journey mashed up against a window, so for the second leg of the flight, managed to change seats and was thinking he was going to be a happy camper. Trouble is, the other guy managed to find out and *also* changed seats so he could be close to his other company executive thus making the entire trip a living hell for Mr. Normal.
(*) I can't say I was a close friend, but we bowled together on the same team for a while and he had plenty of time to tell Dilbertesque stories.