red flag

A red flag is a warning sign that something, or someone, could be bad news. In dating slang it means a behavior that suggests a person might be unhealthy, dishonest or difficult to be with. Online it is often shown with the 🚩 emoji.

What does red flag mean?

Red flags are the things that make you think twice: someone who is rude to waiters, talks only about their exes, gets angry when you see friends, or never keeps plans. Not every red flag is a dealbreaker on its own, but several together are usually worth paying attention to.

People also use it jokingly for small, harmless quirks (“he puts ketchup on pasta 🚩”), which can blur the line between real warning signs and personal preferences.

How to use it

• “He checked my phone on the second date. Huge red flag.”
• “Her ex said she was ‘crazy’ and so was the one before. Red flag.”
• “Doesn’t like dogs? 🚩🚩🚩”
• “Ignoring red flags because he’s cute is my toxic trait.”

Where it comes from

Red flags have signaled danger for centuries, on beaches, racetracks and railways. The figurative sense of a warning sign has been common in English for a long time. Its explosion as dating slang, and the endless 🚩 emoji, came with social media and TikTok in the late 2010s and early 2020s, along with spin-offs like green flags and beige flags.

Red, green and beige flags

• Red flag: a warning sign.
• Green flag: a good sign.
• Beige flag: a quirky trait that is neither good nor bad, just a bit odd or boring.

Related terms

• love bombing: overwhelming affection used to control someone
• gaslight: making someone doubt reality
• ick: a sudden turn-off
• toxic: harmful behavior
• situationship: a relationship with no label

See more terms like this in our dating slang dictionary.