Rihanna. [Photo/Agencies]

Rihanna gave Adele a cake shaped like breasts to celebrate her 24th birthday.

The 'We Found Love' hitmaker sent the sponge cake with pink icing and strategically placed iced gems to Adele's north London home on Saturday (05.05.12) with a cheeky message featuring a topless picture of herself, which she then tweeted.

The message read: "Happy Birthday to my lover Adele."

She also added: "To Adele Laurie Blue Adkins, the baddest bitch around. Have the best freaking Bday. Cake cake cake xxx (sic)."

Adele enjoyed low-key birthday celebrations with friends and her boyfriend Simon Konecki, where guests were asked to bring a box of wine each.

Meanwhile, Rihanna has reportedly been offered £1 million to strip naked for Playboy.

The 24-year-old singer has been approached by Playboy boss Hugh Hefner who thinks her global appeal would improve sales of the adult publication.

A source told the Daily Star newspaper: "Rihanna and Hef are in top secret discussions at the moment. He sees Rihanna as the best music star to have on the cover.

"She is at the top of her game, beautiful, sexy and with huge international appeal.

"Playboy is not a sleazy porn magazine either and allows the stars to get nude in a classy way. That aspect appeals to Rihanna's creative side. Her main concern is that she doesn't alienate her army of young fans who could think this is a little too risqué.

"Rihanna has got naked many times before and is very self assured about her body. In the past she has been snapped topless and not been paid for it. Here she would be earning more than a million for the same thing."