Samgak Gimbap (삼각김밥; Triangle Kimbap) is a triangular riceball wrapped in a dry seaweed sheet. You can try many different flavors with different ingredients inside: mayo tuna, Korean BBQ, spicy pork, BBQ chicken, etc. In Japan, where the dish originated, it is called "Onigiri."
I enjoy buying Samgak Gimbap at a convenience store with instant cup noodles. Because sipping spicy, hot noodle broth each time after biting it makes it easier to swallow and add a better taste. It just tastes better. (These days, I also drink a can of beer along with them.)
I remember the first time I tried it. It was when I was in primary school. Just like a typical Korean high school student, my older brother came back home late after attending a class at a hagwon (학원; a private educational institution a lot of Korean students attend after school). And he was finishing up his Samgak Gimbap in his hand. Of course, as an annoying kid who always stole whatever snack my brother had stashed on his desk, I asked him for a bite. Extremely annoyed yet nice, my brother let me finish it. And It tasted great. I think my love for the dish started back then.
Samgak Gimbap probably became Korean's favorite snack at a convenience store because it is cheap. It costs about $1. Considering instant cup noodles also cost another $1, you can get a decent meal with just $2. (Surprisingly, it wasn't popular in the 80s when it was first introduced from Japan because its taste wasn't what Koreans were used to. And it was also a bit expensive.)
So, if you ever visit South Korea and are on a shoestring budget, why not trying all different types of Samgak Gimbap through the entire journey? Trust me. It won't be that bad at all.