A common device in tales of horror is to make the mundane and ordinary creepy. The more innocent the thing or character, the more shocking its transmutation to evil. Many horror movies or films features evil children (Damien in The Omen), dolls (Chucky in Child's Play), puppets (Puppet Master) and other toys. Clowns and Santa Claus (in Silent Night, Deadly Night) also feature as childhood icons turned evil.
Jensen and Jared both report finding the dolls in 2.11 Playthings scary.
Jared: Dolls. That was spooky. Just walking into a room full of dolls.
Jensen: Walking in with a bunch of dead eyes looking at you.
Jared: Every now and again, one of them was missing one eye, or there was one that didn't have either eye.
Jensen: Just two empty sockets.
Jared: And Jensen was like, "Put your fingers in her eyes." And I was like, "I don't want to. What if something gets me?" For whatever reason, we couldn't force ourselves to.
Jensen: Because you're a pansy.
Jared reports sneaking a doll into Jensen's trailer to freak him out.