Sean Penn on Between Two FernsThank Zach Galifianakis' breakout success in last summer's 'Hangover' for better bookings on his Funny or Die Web series 'Between Two Ferns.' The comedian has now landed Sean Penn to appear in an uncomfortable sitdown. Galifianakis has some different tricks up his sleeve for Penn, appearing as his twin brother Seth, who has a much different manner of Q&A. We could try to explain it, but it's best just to watch. Warning: Some Foul Language