Actor Paul Rudd pulled the best prank ever on a late night show host. Conan O'Brien has actually been on the receiving end of this prank for quiet a few years but no one really noticed, until it was put into a line of video clips.

Usually it's the shows host that pranks the guests but Paul Rudd, over the course of a few years, has pulled the longest running prank ever on Conan O'Brien. He has been bringing with him clips of his current movie to promote, however, when the 'clip' is rolled it's actually from an '80s movie called 'Mac & Me'. The clip has nothing to do with what Rudd is actually there to promote; and he does it with a straight face. It's the same clip every time no matter what current movie Rudd is there to talk about or promote.

Conan gets a little ruffled saying 'will I never learn with you', knowing he's been duped again. Watch his face after each show clip, it's hilarious.