re: Things that you have multiple of, but can't find one when you need it.

I buy every 10mm socket I see at flea markets and yard sales. I just throw them in random places. It doesn't even have to be a place I own. I'll just throw one in a bush along a public sidewalk or leave one in the shitter at the bar. I like to think of myself as some noble Johnny Appleseed character, solving someone's problem before they ever knew they had it.