Actually that's the first time that I heard it. After I looked it up, I found out that it's one of old Korean sayings and surprisingly I have never used it. The meaning is that you end up eating something you don't like. To make a little sense to this, think the '콩' as one of food that you don't like. When you eat food on a plate, you leave the '콩' untouched and eat everything else. However at the end, you even cook the "콩" possibly roasted and eat it up by force or nature. My best guess is that, what this is saying is you can't control your nature or environment from what's supposed to happen. Sooner or later, or like it or not, you will end up doing it. Hope this helps you. .

吃炒豆

eating roasted beans (볶은 콩을 먹고)