There are a lot of Eye Tropes
to indicate someone is going to cry.
There's Quivering Eyes
. There's showing the eyes welling up. There's the multiple blink-blink of blinking back tears.
But there are also mouth cues to indicate someone is about to cry.
There's the lower lip or chin quiver which is pretty much the same motion as a pout, but with the quivering in the lower lip instead of the eyes.
The second is more common to animated fare, and instead of the lower lip quiver, their mouth is drawn as a single squiggly line to indicate someone is about to cry but is trying not to.
And then there's biting or chewing on the lip.
Seen It a Million Times
Anime and Manga
- Pikachu has done the quivering mouth in Pokémon.
- In a number of Robert A. Heinlein stories characters about to cry would exhibit "chin quivering".
- Thorby in Citizen of the Galaxy when he fears his adoptive father Baslim the Cripple is dead.
- John Thomas in The Star Beast, when he and Betty have been captured and he's trying to hold back tears.
- Time Enough for Love. Lazuli and Lorelei Long repeatedly threaten to use chin quivering if people won't do as they say.
- To Sail Beyond the Sunset. When Marian comes to talk to her mother Maureen, she does it before talking to her.
- My Little Pony: Friendship Is Magic: Frequently seen on the Apple family who are very open about their feelings.
- In "The Super Speedy Cider Squeezy 6000", Rainbow Dash gets cry mouth when she is denied a cup of apple cider for the second day in a row after rushing to get some and standing in a long line.
- The Powerpuff Girls also tends to display this trope now and again.
- The Simpsons has a scene where Chief Wiggum consoles a Ralph whose mouth is quivering with sadness.