For some reason I feel compelled to comment on this post from way back in 1973:
"Dear Cecil:
This is a 100 percent serious question, and I want the straight dope. Every night when I’m undressing for bed I stand in front of the mirror and wonder where belly button lint comes from. This is no joke. --John W., Washington, D.C.
Dear John:
What makes you think you have to urge me to be serious, Jojo? Your navel is one of the few places on your body where perspiration has a chance to accumulate before evaporating. Lint from your clothing, cottons especially, adheres to the wet area and remains after the moisture departs."
I also collect quite an impressive amount of lint in my belly button every day, and I was not satisfied by the explanation; it does not explain why my wife, who also has a belly button, does not accumulate lint. Presumably she also sweats in there as I’m sure we all do, but the difference is that she lacks belly hair. I prefer my explanation: the hair on a man’s belly is all oriented towards the belly button and acts as a sophisticated lint collection system that throughout the day collects and delivers lint from the far reaches of the torso and delivers it to the belly button. Once there it cannot escape because the hairs allow movement in only one direction – something like a fox-tail…