Everyday is best day, but the the most beautiful day of my life is that when someone new came to our house and that is my small brother. I still remember the day when he born. When I went to hospital to see him I saw that he was really small and cute. His eyes were big and cheeks are red.
It adds emphasis shows how common it is for them
Maybe it's because we hear it from others everywhere we go. We probably use it to sound cool or to build more words in a conversation.
