দাঁত বার করা মুখ

A yellow face with simple open eyes showing clenched teeth. May represent a range of negative or tense emotions, especially nervousness, embarrassment, or awkwardness (e.g., Eek!).

Resembled 😁 Beaming Face With Smiling Eyes on Apple iOS prior to 2016. Apple’s design for 🥶 Cold Face features the same mouth. Samsung's design previously featured more puckered-looking lips. 

On Snapchat, this emoji next to a contact denotes that you send the most snaps to the same person that they do., i.e., you share a #1 Best Friend.