bite one’s tongue

(verb) to try really hard to not say something

Example Sentences:

When my son told me he wanted to quit university to become an artist, I had to bite my tongue and accept his decision.

Roberto bit his tongue when Sarah told him she wanted to study English in Mexico.

Best Friend #1: I have an announcement to make.
Best Friend #2: What?
Best Friend #1: I’m getting back together with my ex-boyfriend, Bobby.
Best Friend #2: Really? Is this the same ex-boyfriend who dated your sister?
Best Friend #1: Yes, but he loves me again, so we’re going to try to have another relationship.
Best Friend #2: ….
Best Friend #1: What?
Best Friend #2: I’m biting my tongue.
Best Friend #1: Why?
Best Friend #2: Because I think you’re an idiot.

From the Blogs:

Bite Your Tongue: Roadie Rage, and How to Avoid It

Media:

Similar idioms:

1. hold one’s tongue
2. cat got your tongue
3. on the tip of one’s tongue
4. bite me
5. grab a bite
6. make light of
7. fickle
8. knock oneself out
9. bite the hand that feeds one
10. one’s bark is worse than one’s bite
11. grab a bite to eat