I was just buying some food from a street vendor (chocolate covered mini-donuts) and a group of Americans or Canadians walked by and a girl from the group stops, looks over my shoulder and says 'Yum! Those look really good!!'. I just smiled and said 'si', also with kind of a dumb look that spelled out I was a foreigner. Only when they walked away did I realize that they were speaking English and I could understand them. Idiot. I've been blank staring it or listening to broken English for so long, I'm not used to understanding. Again - idiot.