There seems to be a portal from my washing machine to someone elses. That explains why I end up with an even number of black socks, but they differ in material or pattern. Some are the same material or pattern, but a slightly different shade of black. others are identical in every way except for a different color of thread at the toes. A pair of Levi's (size 32 - I haven't been a 32 since high school back in 1968) came through the portal and landed in my washer. Since I lived alone at the time, they remain a complete mystery.