In “Rocky IV”, Sylvester Stallone told Dolph Lundgren to actually try to knock him out. He punched Stallone right in the chest, causing his heart to slam into his breastbone; it started to swell and he was sent to the hospital. The injury is usually caused by a car crash, and therefore Stallone’s insurance almost didn’t cover it because they weren’t convinced it was caused by a person and not a car.