Answer:
Hey! I don't really get why you are asking this, but if it is for an assignment, you could always talk about birthdays, good grades, it doesn't even have to be something big, it could be something simple like your parents or friends congratulating you for something. But if you'd rather know about a personal expirence from my point of view, my friends are proud because I got accepted into a acedimic club that I had wanted to do. They were proud of me, and even though it is something as simple as that, it truly did mean a lot that they even cared for that.
Hope this gives you inpsiration and or helps!