We have really bad take out food here in Iceland. If it's tasty, it's really expensive and generally not something which gets prepared in less than a couple of minutes, but the street food in Serbia is amazing! I really miss it whenever I'm not there, though it also seems custom made to cause a heart attack. It has the typical street food you'll find in most places like Gyros (basically Greek döner kebab with fries), but then it has its own delicacies, like Pljeskavica (similar to burger but different ingredients and gets ready quickly) and ćevapi (little meat rolls often served with something spicy. My favourite of all is Burek. It's incredibly cheap (a 1/4 slice which is basically a full meal is less than a dollar) and is served in almost every bakery, and bakeries then stay open till late in the evening. It's some sort of fatty pastry bake filled with meat and served warm.
Pljeskavica:
Ćevapi:
Burek:
P.S. Just so I don't get murdered, all of those fast food items are common throughout the balkans, and can probably be found in Turkey as well. They are also cheap, quick to serve and can be found all over the place in Belgrade, making them a great street food.