Donald Penn was horse-kicked by Corey Liuget -- and flagged for it

Donald Penn performed the most excusable full body slam in NFL history on Sunday.

Sure, Penn played well through the whistle. But when Chargers' defensive end Corey Liuget horse-kicked him from the ground, he did what any veteran lineman would.

Except the referees didn't agree. They flagged Penn for the late hit -- and not Liuget, whose kick sparked a retaliation.

A league fine will likely rectify the situation. But Penn and Liuget were both in clear view on a charging official; missed calls like that could end up deciding a closer game.

(h/t SB Nation)