Octavia: See that sign? Sheldon: Yes. Octavia: Does it say I give a damn? Sheldon: No. Octavia: That's because I don't. Next!
From this episode on, the dart board on Leonard and Sheldon's door have (most likely accidently) been turned two steps. This makes the 12 go straight up, instead of the 20 (which is two steps clockwise from the 12).