JQ Meaning Confirmed

Yesterday I asked Mrs. Yoon about the 잔머리 thing.  The kids insisted that it wasn't slang--that even their grandmothers would know what it is.  Mrs. Yoon confirmed that, and told us that she was always telling her sons to not be like that.  Apparently many children (and adults too??) think it's a good thing to have a high JQ.  With the kids, they don't seem to understand/care that if you cheat on your homework, how are you going to do on the test?!  The same thing exists in the USA, I guess--do anything to get ahead, if it doesn't hurt anyone you should do it, if it hurts someone but it benefits you then you should probably do it, etc.