Boris Johnson has said he "bitterly" regrets his failure to become a rock star and has admitted to being an "embarrassing dad" in a question and answer session with young people.
London's mayor also revealed that Tony Blair's former bodyguard once took a photograph of his bottom.
But the American-born Conservative dodged questions about which celebrity he had a crush on, pleading the "fifth amendment".
Mr Johnson, widely-tipped as a possible successor to David Cameron, was questioned by First News readers and contributors to the Sky News Stand Up Be Counted campaign as part of the channel's Hotseat series.
The mayor managed to avoid a trap set by the youngsters when they asked him to translate a sentence from Latin, which would have led to him saying he wanted to be leader.
Spotting the ruse, he replied: "I know what you are trying to get me to say."
Mr Johnson then gave the Latin for "I want David Cameron to be Prime Minister".
Pressed on whether he was more interesting than Labour leader Ed Miliband and Mr Cameron, he replied: "I make no comment on the leader of the Opposition who must fend for himself but David Cameron is going to go forward to victory in the next few weeks and I think he is doing a very good job.
"I think he is a very, very competent and expert leader of the country and he is somebody who I think fills the job of Prime Minister very well and I think he should continue to do that, in a interesting way."
Asked directly if he wanted to be Prime Minister the despairing mayor replied: "Good God.
"I want David Cameron to be Prime Minister and he's doing brilliantly and I think he will be re-elected in a few weeks time because I think he has helped to turn the economy round in a very big way."
"So, Dave is going to get back in and I think it's more likely, frankly, that one of you will take over in some dim distant future than I will."
Asked what the "Boris factor" was, he replied "God only knows".
"Turning up is a very important thing," he added. "Always turn up. My strong advice to you, turning up is about 90% of success in life."
The panel grilled Mr Johnson about his biggest regrets, prompting him to put his head in his hands.
"I think I regret bitterly, I still regret, my failure to get anywhere as a rock star and a player of the guitar," he said. "I tried at school to master the guitar with a view to becoming a famous ... and it was hopeless. And I thought, right well I'll master the piano and that went even worse."
Reminded about the time he became stuck on a zip wire, Mr Johnson said it was a "painful" incident and said Mr Blair's former protection officer took a snap of his "rear end" rather then helping him get down.
"I had a bodyguard, which I don't normally have, but they decided it would be so embarrassing if I came to grief during the Olympics that they gave me Tony Blair's ex-bodyguard, who is a very nice guy called Carl," he added.
"After I'd been stuck on the zip wire in stunned embarrassment and personal discomfiture for about five minutes, I said to Carl - is there anything you can do?
"He very slowly took out his mobile phone. He took a photograph of my rear end."
Asked who his celebrity crush was Mr Johnson said he had to be "very careful what I say here" and began to answer but then insisted it was "too embarrassing".
"I'm taking the fifth amendment."
Mr Johnson told the panel he was an " embarrassing dad" and the only things that make him angry are being "beaten at tennis by one of my brothers or sister" and aggressive lorry drivers.
The mayor, who is fighting to the safe Tory seat of Uxbridge and South Ruislip at the general election, dismissed suggestions that MPs should be given a pay rise and said ministers should not hold private consultancy positions.
MPs are "not all twerps" and "most people actually understand that MPs are vital", he insisted.