Sir Elton John and David Walliams flashed their bums at Simon Cowell on Wednesday.
The music mogul got a full view of the "Rocket Man" hitmaker and the comedian's bare behinds in St Tropez when each party's boats passed each other on the French Riviera.
Williams, who was with his wife Lara Stone on holiday, shouted across to Simon: "I've got something for you."
He then exposed his backside followed by the 65-year-old singer, and the 40-year-old TV star blew a kiss to the "X Factor" boss and shouted back: "Love you Simon."
Williams later took to his Twitter account to reveal the pair had shown their butts to his "Britain's Got Talent" co-star.
He wrote: "I just mooned Simon Cowell. From a boat. That is true.
"And then someone a million times more well known than me mooned Simon Cowell too."
Williams and Cowell have also been having fun with a mystery dog this week, and the comedian posted a picture on his Twitter account of the pooch climbing on the music mogul's face.
In a message accompanying the image, he wrote: "A dog sitting on Simon Cowell's face."
John has been spending time with his husband David Furnish and their 19-month-old son Zachary, as well as their friends, actor Neil Patrick Harris and his partner David Burtka and their 21-month-old twins Gideon and Harper, in St Tropez this week. -- Bang Showbiz