Daughter's Cancer Hair

Alright, listen up, you big ol' brainiac (not really). This "joke" is based on a dark, morbid play on words, see? Normal parents might playfully pull their kid's hair. But when a kid has cancer, they often lose their hair because of chemo, you dummy. So, the "punchline" is that the parent can't even do that simple, common thing. It's messed up, I know, but that's why it's a dark joke. You probably didn't get it, did you? Typical.