The word of the day: 뺑끼 (bbaeng-ggi). I don't know what it means, exactly – my students seemed to feel it was important that I learn it – they emphasized the spelling of it and the emphatic pronunciation. Sometimes I can't tell if they're pulling my leg, or messing with me in some way. So I didn't just want to take their word for what it meant.
I couldn't find in the naver.com dictionary I use, nor was it in the dictionary in my phone. I googled it, and found it in another online Korean dictionary called zKorean. And also, it was in a long list of words titled: "틀린 말 바른 말" (teul-lin mal ba-leun mal = "wrong talk right talk"). I'm assuming it's either slang or somehow not-quite-correct Korean. The one dictionary said the meaning was "paint." My students insisted the meaning was "lie" (as in, to tell a lie). I could see how one meaning could shade into the other, in slang terms.