Sheldon: We don't need Howard's cousin, no. We have me.
Leonard: You're not a lawyer, Sheldon, you're just a know-it-all.
Sheldon: I am not a know-it-all. I'm a person who knows lots of things and likes to correct other people when they're wrong.
Leonard: That's the definition of being a know-it-all.
Sheldon: Or in German, a Besserwisser.