Bubbles, Michael Jackson’s pet chimpanzee, turned 40 and celebrated with a party befitting the King of Pop’s pet.“He did get a cake — but it’s a special ape-healthy cake,” said Patti Ragan, founding director at the Center for Great Apes in Wauchula, Fla., the “retirement home” where Bubbles has lived since 2005.“We frost it with mashed bananas and add a little bit of blue food coloring … and then we wrote his name in blueberries,” Ragan said. The theme, fittingly, was bubbles.“We had tubs of bubble bath.