échec, fiasco
It was a complete flop.
Ce fut un échec total.
If you don't do anything about it, the party will be a flop.
Si tu ne fais rien, la fête sera un fiasco.
The party was a flop.
La fête a été un fiasco.
It was a flop.
Ce fut un échec.
— My Friend Ivan Lapshin (1985)