ABC/Jeff LipskyJimmy Kimmel s son Billy turned 7 on Sunday, and the talk show host is thanking the medical staff at two well-known Los Angeles hospitals for the milestone.He and Billy are also paying it forward by raising money for some of the children there."Billy turns 7 today and is doing great thanks to the doctors, nurses, therapists and staff at @ChildrensLA & @CedarsSinai," explained Jimmy, whose son needed surgery to correct a congenital heart defect."Billy is asking friends to give $7 because I m seven to help kids in the hospital, " he continued, adding of his son, "He also wants a spy kit."Kimmel explained Billy s goal is "to raise $100 to help sick kids" and invited others to kick in.Billy underwent his first open-heart surgery at just 3 days old and had another when he was 7 months old. His health took center stage after he was born in 2017, when Kimmel shared with his audience the trials the newborn was facing. "Poor kid.