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]
(..) where's my penis? Oh, it's on the wall over there. Second from the left. I should probably go and find Elaine. She doesn't like being left on her own so You've still got some stuff at the flat. I've been rolling around in my lingerie all over it waiting for you to come and collect it. Yeah, I... (..)2016 TvShow: Fleabag Title: Episode #1.6 Season: 1 Episode 6