A clear case of:
HALLOWEEN COSTUME > NORMAL PROFESSIONAL ATTIRE
The baby's father relayed what happened the next morning to ABC:
"The next morning, he came in to check on Brittany, and he said, 'Sorry I couldn't make it in last night, glad to see the delivery went well.' [He was] joking of course. He also gave her a card of congratulations, and he signed it 'Dr. Joker.'"