"Tây ba lô"
Well, like I said it's old. I haven't heard it used although I am tempted to try it haha. I asked some friends and they confirmed it was something their grandparents would have used. I have doubts this is why the Vietnamese took it up, but it just made me laugh anyway as I am sure some during the resistance against the French were aware of it. https://www.larousse.fr/dictionnaires/francais/ballot/7715?q=ballot#7671
just (western) backpackers. "Tây" means West, or from the West, but it used to refer mainly to French people, language, culture, etc. (because of the colonial era, of course). I think VNmese just use "(người) Tây" for any white tourists nowadays, or Westerners in general. (I don't live in VN, so I can't say for sure if it still the trendy word to describe white tourists. for sure, no one would misunderstand you if you use it)
Yes, "khoai tây" refers to potatoes. Sweet potatoes are also originally from the New World. However, "khoai" by itself seems to be used for both potato and sweet potato depending on context.
Other words with "khoai" :
- khoai lang - sweet potato
- khoai môn / khoai nước / khoai sọ - taro