"Between Two Ferns" host Zach Galifianakis has been known to treat his guests with little regard, often belittling their entertainment achievements. Bradley Cooper, his co-star in the upcoming post-party-disaster flick "The Hangover," recently took exception to Galifianakis's gibes in the form of an open-handed slap. [via Funny or Die]

Check out the altercation, after the jump.