Tomorrow is 복날 (bok nal). It seems to mean that it is start of the dog days of summer. So we'll be eating 삼계탕 (sam gye tang, which is chicken broth with ginseng) to celebrate the day before the rest of Korea does so.
Update #1: You must literally rip the chicken apart with chopsticks and a spoon. It helps to wear a bib so it won't get on your clothes.
The food is cooked after you order it or call ahead with reservations.
Update #2: It is pronounced by me as bok nal, but when I say it Koreans around me don't understand until I pronounce it as "bok nallllllll." This is a common problem with the little Korean that I can say. I'll say it, Koreans will say I speak Korean well, then ask each other in Korean, "What did he say?"
Update #3: James explains that I am probably pronouncing bok nal incorrectly. Instead, it is probably better to pronounce it "bong nahl." I have the feeling I still won't be understood unless I say "bong nahlllll."