They laughed. Apparently picking up Spanish from your Spaniard friend has some downsides.
As in South American backpackers find it funny/amusing this drunk Chinese guy in an Australian pub used the Castellano equivalent of "y'all" in a sentence.
They were ultimately nice about it, much better than the time my (English speaking) Canadian coworker tried to speak to some Parisians in school level Québécois and they scoffed and continued in English.
It's also fairly casual, it's the informal form of ustedes, which LatAm doesn't even have anymore.
So it'd be more like if you ran into someone who not only was using British English, but specifically spoke Cockney and used the phrase "apples and pears" to refer to stairs completely unironically, on the complete other side of the planet.
I can kinda see how that would be funny.
If it's an informal form of "you" fallen out of use, wouldn't it be more like someone unironically using "thou" in a sentence?
It would be more like if most British people still use thou and insist Americans, Canadians, Australians, etc are wrong for not using thou.
Haha 😂 I see now.