Best Answer

Cats bury their feces and urine by digging in order to hide their scent to protect themselves from discovery by predators. They will also do this with the feces and urine of their kittens. It's a natural instinct which Oscar has extended to your dirty laundry. You have left your scent behind on the sock, and Oscar is burying it to "protect" you. It's just a normal cat instinct that is manifesting in what is an odd way to us, but perfectly natural to Oscar.

Put something heavy on the lid of the laundry hamper so Oscar can't kidnap your dirty socks. But just know he's only doing it to protect you!

Schmoo answered on Mar 18th.