Simon Cowell -- The Pecs Factor

Despite snagging Britney Spears and Demi Lovato for "The X Factor," former "American Idol" honcho Simon Cowell has hit a new low ... cut top.

While arriving to the "Britain's Got Talent" afterparty at the Dorchester Hotel in London last night, the 52-year-old mogul -- and his pack of Kool cigs -- nearly had a nip slip as his severely unbuttoned shirt showed off his sexy hairy man-bosoms.