This Zufällig fankunst contains
anime, comic, manga, cartoon, comic buch, karikatur, and comics.
There might also be
zeitung, papier, magazin, tabloid, rag, zeitschrift, lappen, and boulevard.
Jimmy's reaction makes it OBVIOUS that he knows what it is. Unless you've lived under a rock for your entire life Du would never see that triangular symbol and be like "gang symbol?