Face or someone's expression. It also describes a person with extreme audacity or nerve who does shameless things without a care in the world.

To flirt without commitment, to be in that limbo with someone where you're not together but not just friends either. The classic 'we have a thing but we're nothing official.'.

Total nonsense, a huge blunder, or an idea so absurd it defies all logic and common sense. It's the natural reaction when someone proposes something completely ridiculous.

To publish someone's personal information online without their consent: real name, address, phone number. It's one of the most dangerous forms of digital aggression.