"When you have to go No. 2 in an airplane bathroom, flush while you go, then flush after you go," he says, referring to the widely known practice of the courtesy flush. "Then -- you laugh, but this is effective -- use hand soap. Put it on your hands and all over your arms, and do, like, tai chi moves with your arms." This gets the smell of the soap in the air and covers up whatever other smells might be there.
"Then wash your hands, and then the bathroom doesn't smell like your stuff. Every time I do it I'm impressed with myself."