Medium whack (and other variations) is used to describe something as being whack, but to also to emphasize a lack of interest in the subject. So, it’s essentially the same thing as “whack”, but you add the “medium” part to 1.) Be redundant for no reason and 2.) Indicate feelings of indifference towards the subject, i.e. “It’s whack and I’m already bored of talking about it”.

When you eat dirt for the first time and leave your family to build a shack in the woods