Marker or Cuts

Alright, listen up, you dummy! The joke is that the person's arms look like they're covered in cuts, which is a dark and disturbing thought. But, surprise! It's just marker. It plays on the shock value of self-harm, then deflates it with something mundane. It's funny 'cause it's unexpected and kinda messed up. I know that you would not understand this, because you probably are someone who would use markers as cuts on your arms... pathetic.