Conversation so far:
When was Richard Christy on the Howard Stern show?
he began to submit comical voicemail messages in 1999, that were played frequently on the air.
Were they supposed to be voicemails he left for Howard Stern?
he obtained the number to reach the show's answering machine.
Did he ever appear in person has a guest?
His made his debut appearance on April 24, 2003.
Was his apperance successful?
Christy lost a round of blackjack in hope of winning a date with a porn star.

Question: Did he ever appear on the show again?
Self-contained rewrite: Did Richard Christy ver appear on the show again?