The surprise announcement of his candidacy 'caught' his opponents 'flat-footed'. [=his opponents were not prepared for his announcement]
The battery has gone 'flat'. [=('US') the battery is dead; the battery has died]
She finished her homework 'in nothing flat'. [=in no time at all; very quickly]
(..) Why? I need to rub my genitals on their prototype. What's going on? Leonard and Howard don't have a flat. They went to the movies. Look. Son of a bitch. Un-freakin' believable. Oh. You know what? I'm gonna let them know (..)2016 TvShow: The Big Bang Theory Title: The Solder Excursion Diversion Season: 9 Episode 19
(..) look bad. (phone chimes) Oh! The boys had to drive all the way to San Bernardino for the solder and got a flat. (phone chimes) They bought it. But we're gonna have to put the spare on before we go back. (..)2016 TvShow: The Big Bang Theory Title: The Solder Excursion Diversion Season: 9 Episode 19