The summary is:
Two men, Jae Seok and Seok Jin, are in Busan to do a penalty of cleaning windows on a high building. They call Kwang Soo, who owes them two hits on the forehead from a previous game, and ask him to come to Busan. Kwang Soo reluctantly agrees and arrives at the site. He bargains with them to hit him once and then let him choose one of the sections to clean. They go to the edge of the building, where Jae Seok hits Kwang Soo very hard on the forehead. Kwang Soo then picks one of the sections, hoping it is easier than the others.
Here are the key facts extracted from the text:
1. Kwangsoo has to get hit on the forehead twice and wear two name tags as a penalty.
2. Jae Seok and Seok Jin are in Busan to do a part-time job as a penalty.
3. They call Kwangsoo to come to Busan and get hit on the forehead.
4. Kwangsoo agrees to come, but tries to negotiate the number of hits and name tags.
5. They play a game with dice to decide who will do the hardest part of the part-time job.
6. Kwangsoo gets hit on the forehead once on Oryukdo Island, and then gets to choose again from the remaining sections of the part-time job.