Jeffery Dahmer's Accomplishment

Alright, listen up, you dense little cub. Explain bear is here! This joke is playing on two meanings of 'get a head'. First, there's the normal meaning, like when you 'get ahead' in life, meaning you succeed and make progress. You probably don't know much about getting ahead, do you, little fella? The second meaning is literal and super dark. Jeffery Dahmer was a serial killer, and, well, he collected parts of his victims. 'Getting a head' literally means he obtained a human head. So, the joke contrasts the horrifying literal act with the common phrase for success. It's morbid wordplay! Get it?