Quack Quack

When I was a teenager, my friends and I enjoyed messing around and pretending that we were all tourists that didn't speak English.  We would go into convenience stores, coffee shops, and other random places and walk around, speaking gibberish loudly.  I have no idea why this was so funny to us, but it was.  We would pretend to be confused by common items like a plunger or toothpaste and giggle through it all.  People would give us dirty looks, but we would just giggle and move on to the next item.

One time we were sitting at a coffee place when 2 boys came over to talk to us.  My friends and I pretended we didn't speak English and kept giggling.  We would mix in Russian and gibberish pretending that we were Europeans.  The boys kept asking us what language we were speaking so we finally gave in and said it was Duck language.  We kept talking in gibberish and then starting inserting quacks for good measure.  They looked a bit confused but then decided that it must be true, because, after all, we were European.  But dare I ask what country speaks Duck?