If you're walking around Wenceslas square you cannot help but notice the many stalls selling sausages and other quick meals. The sausages are surprisingly nice but the best thing in my opinion is the fried cheese served in a bun with mayo and a leaf of green salad. Cheap, oily, filling and the best thing in the world when you're drunk. It was also featured as a thing to do in Anthony Bourdain's No reservations episode on Prague and I think he nailed it.