11/05/2006 AT 10:30 AM EST
Sean 'Diddy' Combs turned 37 on Saturday – and he's expecting twin girls
with girlfriend Kim Porter – but he's still a kid at heart.
At Paper nightclub in central London to celebrate his birthday and promote his new album, Press Play,
Diddy told PEOPLE that he likes being a young dad. "I can relate so well to my kids," said the father of Justin, 12, and Christian, 8. "I mean, we like the same sneakers and listen to the same music and go to the same movies, so there's not that generation gap. So it's like being a parent, but also being a friend."
Dressed in a gray three-piece suit and dark sunglasses, Diddy presented a birthday surprise to the 200-plus crowd: A duet performance with Kayne West.
The two looked like best friends as they danced and sang side-by-side under blue strobe lights until the wee hours.
At one point, when West broke into his hit "Gold Digger," Diddy threw stacks of mock $100 dollar bills, with Diddy's picture in place of Benjamin Franklin's, into the air.
He did cough up real coin when he asked the bar staff to "break my pockets" by offering "a $1,000 tip" to pour tequila and lemon drop shots for everyone.
As the birthday bash drew to a close, Diddy told the crowd: "If you wake up tomorrow and your head is spinning and you wake up with five young ladies in bed – or ladies, you wake up with two men beside you, then call your man Diddy and say, 'Thank you, Diddy. I love you, Diddy.' "