The Janitor is a character on Scrubs played by Neil Flynn.  His real name is unknown and he is simply referred to as the Janitor on the show.  He is constantly lying and torments J.D. every day.

The Janitor Quotes

Don't mean to bother anybody. I'm just showing nurse Martinez here around the hospital. That's our chief of medicine, that is a patient, and that is you in twenty years. Okay, let's go look at dead people.

Janitor

Janitor: I know we haven't care of that whole asbestos thing from the '90s, and I know some toilets flush upward...
Dr. Kelso: Get to the point. My battery power's running low.
Janitor: The one thing that I'm proud of is that these floors are so clean you could eat off of 'em.
Dr. Kelso: Why is that?
Flashback
Janitor's Mom: If you're going to throw food on the floor, you can just eat there from now on.
End Flashback
Janitor: Soup night was the worst.

Scrubs Quotes

J.D.: We found you in the park throwing rocks at old couples...
Ted: Why should they be happy!?

J.D.'s Thoughts: Wait, is she in to me? Quick, make a bad joke and see if she laughs.
J.D.: Did you hear the one about the skeleton who couldn't go to the party? He had no body to go with.
Neena: That's really funny!
J.D.'s Narration: Well that's not a fair test - that joke's hilarious.