This should have been a red flag to everyone, regardless of what they thought of Fox News.
Similarly, the man caught on camera changing his shirt might as well have waved a red flag.
The bigger the claim made in the headline, the bigger the red flag it raises for me.
Subject of a special warning or suspicion: His article identifies several ''red flag'' professions that have a higher-than-usual chance of being audited
[1976+; found as a sign of warning by 1777]