Red Hot Chili Peppers frontman Anthony Kiedis lost his virginity at the age of 12 to his father's girlfriend.

The CAN'T STOP asked his dad's permission during a night out together - and he agreed.

LARRY SLOMAN, ghostwriter of Kiedis' new autobiography SCAR TISSUE, tells PAGESIX.COM, "Anthony's father, who took the name BLACKIE DAMMET, was once a big-time coke dealer and he was the king of the Sunset Strip in Hollywood.

"His girlfriends were always young, hot girls.

"One night, when Anthony was 12, he went with his father to the Rainbow Room and Blackie's girlfriend is there dancing for him.

"And Anthony asks, 'Dad, can I have my first sexual experience with your girlfriend?' And Blackie says, 'Sure, son.'

"So they go back to the house, and his dad builds a big bed out of four mattresses in his room and puts the girl in next to him.

"And that's how he (loses his virginity)."