Starr, known as The Regurgitator, was shown at the weekend leaving judges agog when he placed coins and a billiard ball in his mouth for his audition before bringing them back up.
Asked what the strangest thing he had ever put in his mouth was, Stevie said: "A poisonous frog in a bar in New Jersey. I did it for a bet from the barman who was trying to be very nonchalant about my swallowing ability."
On whether the Royal Family would enjoy his talent, Stevie, 47, said: "I'm sure, like everybody else, they would find it mind-blowing. Is that the same as enjoying it? I don't know."
Praising the judges, he said: "I loved seeing their faces and I was impressed that Amanda (Holden) was able to overcome her natural revulsion and appreciate my talent.
"I thought Simon (Cowell) would be the hardest to impress but he seemed very 'on side', too. They were all nice to me, so perhaps I am biased in thinking they were all good guys."
Asked if he had had any near-death experiences while performing, Stevie, a veteran on the variety circuit said: "Absolutely not. I know my limits and I am always in total control."
Acrobatic gymnast group Spellbound are the red hot favourites to win the show, with William Hill slashing their price from 11/2 to 4/1.