I had to throw out a pair of socks the other day.
Normally, when a sock has a hole in it, and you want to get rid of it, you have two options.
(1) Throw away the other sock as well. I feel a little weird doing this; it seems somehow wasteful to throw away a perfectly good sock.
(2) Keep the other sock. This can be annoying, though, because then you have an odd number of socks, and the sock that you keep might almost, but not quite match some of your other socks.
Fortunately, though, this time around, both socks in the pair happened to develop holes in the toes at the same time, so the decision was made for me with no unpleasant consequences! Isn't symmetry wonderful?