Why does lint go into your belly button? :wally
For the same reason you have toe cheese! Lint from particles on clothes finds its way in there and kicks it! 
[ol]
[li]Your clothes “erode” tiny bits of fabric from rubbing against your body[/li][li]Your belly button pools sweat (if it’s an innie)[/li][li]The fabric “dust” sticks to the sweaty parts of your body, not just belly button[/li][li]Small, concave shape of navel wads up all the fabric dust into a lint ball[/li][/ol]
What AWB said, and Cecil too: http://www.straightdope.com/classics/a1_080.html