Analphabet way to say: "qué?"...
(Since Spain was mostly country side, and instead of going to school, children stayed at home to help with the: animals, housework... and families lived all together: children, parents and the parents of the parents, where the older had the "voice" in the house, and a bad language, analphabetism was learnt at home
"¿vamos a beber unos choticos al bar, Pepe?
Pepe: "¿lo cualo? ¿al bar del sosio?
But that changed a couple or three generations ago, but youth use it as "slang" or joking.
And since YOUR WORD is written with "K", that also says that is a way of very-informal-joking way to say ¿qué?