When I was an exchange student in Mexico, I spoke Spanish, but I kept translating idioms from the U.S. into Spanish.
My mom grew up on a farm and I live in a somewhat countrified part of the South, so I use a lot of animal idioms, like "pouring sand down a rat hole," "parking lot vulture," stuff like that.
They were like, whaaaa? I'd tell them about how there were deer wandering around the yard and coyotes and foxes and eagles and stuff and they were like, whaaaaa?
They reacted like I was living in some crazy zoo or something, like the Wild Kingdom popped outta the TV.
Plus, they thought it was HILARIOUS when I'd say "horrible" in Spanish because they said I sounded like this TV character on this goofy show where it was a classroom full of adults playing little kids and one would say "horr-iiiiiiii-ble!" and then I saw it and I totally saw what they were talking about.