Hong Kong people used the term "AA 制" to ask their friends paying the money seperately, in fact the word and the origin is not occur in English, this term is only popular in Hong Kong.
Mainland site said: "Hong Kong waiters will ask the customers "all together or all apart?" while checkout the bill." This is inferred AA from "all apart".
In reality, if you would like to ask your friends to pay money theirselves, English can be expressed in terms of "Go Dutch" and "Split the Bill", but they are a bit different.If someone ask you wants to " Go Dutch " ? It is asking if you want to pay by your proportion on you own and " Split the Bill" means the total number of bills share equally of each person.