Falling prices may be a 'warning sign' of a recession. [=may indicate that a recession is coming]
There were storm 'warnings' [=warnings that a storm was approaching] issued for the area.
I'm giving you 'fair warning' that you had better not discuss politics at dinner tonight.
(..) because I'll talk to the elders and we'll work it out. It's no big deal, okay? Come give me a hug. What do you mean she didn't read the warning? I'll explain later. The bottom line is we need you home now. Well, I can't, I'm kind of in the middle of saving Richard right now. Be right with you. (..)2004 TvShow: Charmed Title: I Dream of Phoebe Season: 6 Episode 15
(..) - I thought she was an innocent. How was I to know that I was gonna unleash a demon? - It says so right here. - Oh, right. Right there, in Arabic. There's a warning label on the genie bottle? Yeah, an ancient sorcerer condemned a demon into the bottle for not marrying him. (..)2004 TvShow: Charmed Title: I Dream of Phoebe Season: 6 Episode 15