stunned fans by singing an impromptu tribute - to Mariah Carey
) boobs. The Coldplay
) frontman made up the song after a reporter asked him if he thought the curvy diva was "on his tail" in the race to have 2005's best-selling album.
The star, who was giving a private concert for winners of a radio contest, joked: "She's not, but one of her boobs is. They do most of her work. Last week I was chased down the street by an enormous boob. I think it was hers."
Martin, who is married to actress Gwyneth Paltrow
, then started singing: "Mariah Carey's boobs are so nice, and she doesn't mess around. If she had been aboard the titanic, there's no way that ship would have gone down."