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.
(..) Take it. Take it, take it. Make the trade. Make the trade! I'm so sorry. I'm sorry, yeah. This is your last warning, then I have to ask you to leave the hall. I understand, yes. I'm sorry. I'm so sorry. Just, please. Don't fall for that. (..)2014 The Dark Horse