Say cheese

When someone asks you to "say cheese," they usually want you to smile and show your teeth to take a nice picture. When we smile, our brains tell our facial muscles to move in a way that makes us look happy and friendly. Showing our teeth in a smile can make us look even happier, and it's a very common thing to do when taking pictures. So, when someone asks you to "say cheese," they want you to show your teeth in a big smile so they can take a cute or happy picture of you!