It worked!

In honor of April 1st, I began class today by playing a song in Dutch (which I of course told my students was a French song) and asked them (in French) to write down the lyrics. They didn't write anything. I feigned surprise and asked them pourquoi, and one of my students explained that the song was probably from a different region of France, perhaps near Germany. Another suggested this might be Belgian French, which was getting there, but... They were stunned to know that what they had been listening to wasn't French at all, or at least they feigned surprise convincingly.