faire un tabac

to be a huge success

Said of a show, song or product that catches on in a big way with the public.

Ce film a fait un tabac au box-office cet été.

This film was a huge success at the box office this summer.

The 'tabac' here has nothing to do with tobacco. It comes from an old Occitan word, tabastar, meaning to hit hard, which also gave French 'tabasser' (to beat someone up). Early 20th century theatre slang used it for a thunderous round of applause, and the sense of a smash success stuck.