No, the title does not refer to slot machine sounds even though slot machines can probably be found in some chim chil pongs. The term refers to a Korean spa, which in my case was Dragonhill Spa in Seoul.
This particular Chim chil pong was apparently one of the best in Seoul. It consists of separate bathing floors for men and women; in addition to 3 different temperatured baths, there was ginseng, herb and seasonal herb baths, massage bath as well as additional beauty services such as massages, body scrubs and hair removals that could be purchased for extra cost.
When entering the spa, you get clothes for the public area, and a locker key that works as money inside the spa. After soaking in the baths and enjoying the saunas (infra red and one that had mist spraying from the ceiling), most people go to hang out in the arcade, public space, cafes and various hot/cold rooms that are located in the common areas.
You can spend 12 hours in the spa with no extra cost, so people go there to hang out and spend time with family, sleep after going out to party, or to go on dates (some of the small rooms seemed to be very nifty for that purpose). Our initial plan was to sleep in the spa but since it was crowded (Saturday night) and home was near, we opted for a good solid sleep, though there was also a sleeping room for women only.
Going to chim chil pong is definitely worth it, since you get to experience the way Koreans spend time. It is a cheap option for hotel (12,000 won: approx. 10e) and definitely interesting! If you intend to stay for longer than 3 hours, I suggest bringing a book or something to occupy yourself with. During the wee hours of night, the atmosphere might get gloomy.