To prove how important diacritics are in Vietnamese writing, here’s a conversation I had on Facebook that started out with a haircut, but could mean totally something else depending on how dirty your mind is:
John Smith Ban thich cat ngan hay cat dai?
Donny Truong Writing Vietnamese without “dấu” is quite dangerous.
John Smith And sometimes so confusing that it makes people ask you over and over for clarification. You answer and answer but they keep asking, asking. Cu hoi, cu hoi, cu hoi hoai! Until you get upset and want to chui lon!
Donny Truong Du roi, du roi. Dung chui lon nua.