Why did USC's Josh Shaw lie?

A college football player sprains both his ankles jumping from a balcony to save his nephew from drowning. At least that's what USC cornerback Josh Shaw told his coach. It turns out not to be true and Shaw is now benched indefinitely. So how did he sprain his ankles? Sara Sidner has the latest.

Why would anyone tell a huge lie like this? Dan Ariely is a professor Psychology and Behavioral Economics at Duke University.