About speaking:
* Put your foot in your mouth: To say something embarrassing or inappropriate.
* Bite your tongue: To refrain from saying something, even though you want to.
* Have a big mouth: To talk too much or reveal secrets.
* Keep your mouth shut: To stay silent, not talk.
* Words out of your mouth: To say something unexpected or surprising.
* Spit it out: To tell someone something quickly and directly.
* Sweet talk: To use flattery to persuade someone.
* Talk your ear off: To talk excessively and for a long time.
* Talk a blue streak: To talk continuously and rapidly, often about something that is annoying or unpleasant.
About eating:
* Water in your mouth: To be very eager to eat or drink something.
* A mouthful: A large amount of food.
* Eat your words: To admit that you were wrong about something.
* A taste of your own medicine: To experience the same treatment that you have given to others.
About other things:
* Mouthpiece: Someone who speaks on behalf of someone else.
* Mouth breather: Someone who breathes through their mouth, often considered unattractive or unintelligent.
* The mouth of the river: The point where a river flows into a larger body of water.
* A bad taste in your mouth: An unpleasant feeling, often caused by something you have said or done.
* Get something down your throat: To make someone do something they don't want to do.
Humorous:
* Talking out of your hat: To say something that is not true or based on evidence.
* Run your mouth: To talk a lot, usually about something that is not important.
These are just a few examples, and there are many other idioms about the mouth. The meaning of an idiom can vary depending on the context, so it's important to pay attention to the surrounding words and the speaker's intention.