Tanguy is 28 years old and still living with his parents. They think it's time he moves out. He doesn't, so they hatch a plan.

For Pierre Brochant and his friends, Wednesday is “Idiots' Day”. The idea is simple: each person has to bring along an idiot. The one who brings the most spectacular idiot wins the prize. Tonight, Brochant is ecstatic. He has found a gem. The ultimate idiot, “A world champion idiot!”. What Brochant doesn’t know is that Pignon is a real jinx, a past master in the art of bringing on catastrophes...