Here's how it works:
* The image: The phrase conjures up the image of someone biting their tongue, as if holding back from saying something harsh or critical.
* The meaning: This visual cue implies that the person is not being genuine and is saying something contrary to what they truly think or feel.
Examples:
* "Oh, I just *love* being stuck in traffic for hours. *Tongue in teeth.*"
* "That's such a *great* idea! *Tongue in teeth.*"
* "I'm so happy to see you! *Tongue in teeth.*"
Note: It's important to use this phrase sparingly, as overuse can make it lose its impact.