dîner des cons

… was a popular french theatre play that became a french movie classic. The comedic play centres around an idiot-character who is invited to dinner by an upper-class group specifically for this reason — that he's an idiot. The actor — a word synonymous with comedian in the french lexicon — playing the idiot is a well-known french humour-actor who was in fact depressed in real-life and is now deceased.

ADDENDUM :
… has now been adapted to hollywood as “dinner for schmucks.”