Girlfriend says:
Theory:
You do laundry with a few pairs of blacks socks. Since like most people you don't own that many socks you wash them along with other articles of clothing, like jeans and sweatshirts or shirts. When you dry, and find you are missing a sock, more than likely one of them is inside a pant leg or in the sleeve of the sweatshirt you washed.
Fact
You never lost that sock, you misplaced it and since socks are not individual items when you see one you are seeing them both(!!!??). Say for example you find one white sock (sigh) you throw it in the drawer beneath your normal sock drawer becuase it's not a pair any more. Then 2 weeks later your doing laundry and you come across it's mate, but you've forgotten about the fact that the first one was missing so you think it's another missing sock. You throw this into the second drawer that is now disorganized becuase lets face it guys dont fold all their clothes. So now you've got two socks on separate sides in one drawer and thats when the Boogy Man comes in and grabs the unmatched sock and the lone sock remains. Simply to drive you mad and make me type this entire sock theorum.
(no more coffee please)