I have to admit that the subject of this thread threw me for a loop. I was sure it referred to a Kvittel one gives when going to a Rebbe. 🙂
I have heard that the idea of playing cards is related to “leil nittel” when there are those who have a minhag not to learn (although, I suppose any batlan who spends his days in Vegas can claim he is super machmir and observes this minhag year round!) although I have no idea how the minhag of playing cards evolved. Why didnt everyone just stay home and read a good book if they werent going out to learn?