Funnyman Jonah Hill wasn't laughing when he overheard medics talking about amputating his arm when a teenage joyride left him with a shattered limb.
The Superbad star still bears the scar of the near-fatal accident that reminds him of his wild youth, when he "was not a good kid".
Hill tells Rolling Stone magazine he started behaving badly because he was convinced his mum was going to lose her cancer battle - and his life almost ended one night.
He recalls he was 15 when he and a pal took off on a late-night drive and flipped over a Sports Utility Vehicle. Hill had his arms stuck out of the window at the time and it was dragged along the road.
Hill woke up in the hospital, and he heard two doctors discussing whether or not to amputate his arm. At the same time, he saw his dad and ailing mum crying.
He says, "I said to myself, 'I'll never let them down ever again... I'm going to be f**kin' successful. I'm going to resurrect what I put these people through by being a little a**hole.' So I look at this scar every day. That reminds me to work hard."