My two-year-old Bengal puts everything that he likes in his water dish. I read that some cats do that because in the wild, they keep things that they like in their "nest" for safekeeping, and so domesticated cats may use the water dish as their place for safekeeping (presumably because they see the water dish is their property). I'm not sure how that applies to socks, tho!
If I'm unable to find an earring, or anything else small and shiny, it's very likely in his water dish. Curiously, he also seems to have an affinity for Kleenex tissues. He will literally pull as many as he can out of the trash (eew!) or out of the box, and then wet and shred them in/around his water dish.
He also has great affection for anything he can find in a plastic bag, and for plastic in general. Not the grocery bag variety, but the shiny kind, like Zip Lock bags are made of.
Has anyone else experienced or heard of the plastic or Kleenex tissue, uh, issue?