Like tu and usted in Spanish, or ??? and ustedes.
Once in 1971, I met a pretty girl on the street in Guatamala City, and when I asked directions, she didn't seem to be in a hurry, and I wanted to get to know her, but the conversation ended. Later I thought she might have been put off because I kept addressing her as usted instead of tu, which was by then the standard among people our age. But I had learned Spanish starting only 5 months before, and usted was one of the half-dozen words I knew before then.
Someone in the hotel I was staying at spent a full 5 minutes teaching me how to say periodico in Spanish (I think I kept saying the I as a vowel), and a guy on highway crew that picked us up hitchhiking spent 5 minutes or more how to say a V that is half-way betweeen a B and a V, v-vaca vs b-burro.
I can't remember what it is now but there was some word I learned to say from cowboy movies (that is, any Western movie about the late 1800's) and later I found out Mexicans pronounced it that way in rural areas, but more simply in the city. So the cowboy movie set in the countryside was right. I think it was a nasal "sing song" up-pitch at the end of "Si, senor".
LOL I think I never heard that word until I was 10 years old. There was a group of words I'd never heard until we moved to Indiana when I was 10, reflect meaning to think, etc. The teacher Mrs. Tune used them and to myself I called her Looney Tune becuase of her strange language.