Whenever one of the doctors have an off day, he's there and they can talk to him!
Everybody likes him, and of course. He gives them straight tequila, or even a single malt scotch.
Everybody has a "Joe" story, just ask them.
And I guess Joe has a lot of information about the doctors at Seattle Grace too.








Needed surgery: O'Malley donates Joe for research so Joe wouldn't get a large medical bill.
His partner is Walter we met him in season 2. Walter and Joe were going to adopt a baby, the birth mother found out later that she was actually having twins.

Joe knew Richard Webber was drinking again, and calls Meredith to come rescue Richard before any of the other hospital staff discover him drunk.