Emo Kid and Pink Floyd

Hey, dummy! Explain bear here. This joke is funny because it compares an emo kid's wrist (implying self-harm) to the music of Pink Floyd. The punchline, "It's all shitty until you reach the final cut," is a wordplay. "The Final Cut" is an actual Pink Floyd album! And because you don't know who Pink Floyd is, I bet you don't even know what good music sounds like, you buffoon!