I have sometimes wondered what would be the appropriate way of addressing (fellow) students that are junior to oneself. Given name? Full name? Name + 妹/第? Are there even cases where one can use 哥/兄 ...
For female waiters, my dad taught me to use the phrase "小姐 ". But for male waiters, my dad doesn't know how to properly call them. I discussed the possibility of using "da ge", "小ge", "da di", "小 ...