Andy Bates is the Jonathan Coulton fan who was chosen to perform the "MESSAGE REDACTED" line in "Chiron Beta Prime", as well as the vocalized keyboard solo and harmony during the final chorus at the February 22, 2008 San Francisco performance. He subsequently appeared on the Best. Concert. Ever. CD and DVD.
During the This Week in Tech podcast (episode 133), Jonathan would later comment that, when Andy stood up to volunteer, "he was, like, ten feet tall, and I was like, 'Okay, that's my guy.'" This was in part because Andy had attended a previous concert where he missed an opportunity to volunteer, and made a conscious decision to do anything possible to get another chance.
Andy's tale for even getting to attend the concert was a message board legend. He initially did not buy a ticket because he already had a family vacation planned for that week. A few weeks before the concert, Andy had to cancel his vacation and began searching for tickets but the show had already been sold out. Andy emailed Jonathan to ask for a ticket, but Jonathan said that he no longer had any tickets available, and suggested asking on the forums. Finally, in a thread for people who were planning to attend the show alone (which became Single Concertgoers Attending Together), one person had an extra ticket. Andy won the coin-flip, and made it to the concert.
Andy also created one of the winning entries for the t-shirt contest.