A person who humors the attention whore by giving him or her exactly what he or she wants - attention. In essence, the attention john gives the attention whore business, much like a regular whore-john relationship.
Jeb: Poor Bobby had an asthma attack when the elevator became stuck.
Fran: It wasn't real. He faked it. He doesn't even have asthma!
Jeb: I won't listen to this! I'm going to go comfort Bobby and wait on him for the rest of the day!
Fran: You are such an attention john!