"Faire un bide complet" is "to be a total flop" or "to bomb".. Basically to fail miserably.
"C'est le bide complet" means "It's a total flop/washout/failure"
Le bide is a concept, one could say a tool, of Lecoq's teaching method, particularly for the Clown. It is to take the fall, be completely lost, hit rock bottom, to dry completely on the stage. It is the zen of total ego loss. To find oneself there in front of the audience, so vulnerable, so transparent, so devoid of resources that suddenly anything and everything become possible. There is no way left to go but up.