My best language story happened in Italy. My wife and I were on our way back to our hotel in Orvieto when we came across a Carabinieri checkpoint. I knew I hadn't done anything (or thought so) because we came around a curve and there he was, resplendent in his uniform, helmet, sunglass, looking like Apollo about to swat a bug. I pulled over and rolled down my window. He said something which, of course, I didn't understand, so I told him "No hablo InglÚs". He looked at me for a moment, stepped back from the car, his head sank to his chest, and he pointed for me to go on. I thought this worked pretty well and drove away. As soon as I got the window back up my wife busted out laughing.
"Do you know what you just said?"
"Yeah, I told him I don't speak Italian."
"No, you just told him in Spanish that you don't speak English!"
Well... it worked. And I bet he still tells that story, too.