where have all the socks gone?

this is something i ponder every week when i do laundry. i realize that the subject is very trivial, but i can't help it. i separate my laundry and when i do i always make sure that i have an even number of socks. so why is it that when i take a load of clothes out of the dryer, i am always missing a sock? i check between the washer and dryer, the missing sock is not there. where do they go? i know my kids would love to think that there is a "sock" monster of some kind that reaches in and takes one. just to make things difficult. they must go somewhere and i wonder where???