“Duck face” dominated for a long time. That’s where you pout your lips like a duck. But that’s old news.
To pull off scrunch face, you have to scrunch your nose, squint your eyes, and flash a grin. If you do it right, it’s supposed to look cute. (If you do it wrong, you look like you ate too much cheese and haven’t seen a bathroom in days.)
It’s also kind of like the face you’d make if you just bit into a lemon. So it’s not exactly a new facial expression.
People have actually been doing it on social media for a while. But it’s hit a point where kids do it compulsively now, without even thinking. So it’s all over social media.