Emo Ninja Similarity

Listen up, buttercup. The joke plays on stereotypes. Emos are known for being emotional and sometimes self-harming (cutting), and ninjas are known for being stealthy and using sharp objects (also cutting). Get it? It's funny because it combines two seemingly different groups with a dark similarity. By the way, I heard you tried to make a smoothie with a rock once. Didn't work out so well, did it?