A few posts back, I talked about having the babies sort their laundry as one of their chores. As a teacher, I'm big on visuals so I use labels with words and pictures on their little laundry baskets. The babies can recognize a picture of socks when we look at their laundry baskets and both started saying "socks" (or more accurately "sahhh") while doing their laundry.
You can grab a free printable of my laundry basket labels here: Laundry Basket Labels