I suspect they have twelve such banners, because a similar deal was in effect when our occasional "Western Seoul Dinner Club" visited a few months ago. That's me, The Stumbler, Nick, and this time, Choro. Members emeritus include Kevin, Lynn and Helen.
There are five million photos of "Korean Barbeque" online--make that five million and one. 갈비살 is rib meat, at 150 grams for 11,000 W. When you make that a 2 + 1 deal, four people ate and drank to satiety for 64,000 W. I have eaten at regular price places where the galbi is fair to middlin', but despite the price the quality here was really good. More potatoes and onions for the asking.
Here is the menu, and a fun sign to the 화장실: