Sheldon does not have a cousin Leo.
The Big Bang Theory Season 1, Episode 10
...emotionally wrung out from the work
of convincing Leo to go back into rehab.
The Big Bang Theory Season 1, Episode 10
Leo, you are a very sweet,
really funny guy.
The Big Bang Theory Season 1, Episode 10
Well, that's Leo.
The Big Bang Theory Season 1, Episode 10
There's no Leo. How can you say that?
The Big Bang Theory Season 1, Episode 10