It's about a guy trying to get in touch with his drug dealer. The narrator mentions that "Katy tried, I was halfway crucified." Katy, in this case, is a drug that almost killed him (most likely heroin.) Dr. Wu is the nickname of the the narrator's dealer, but at the time of the song, Dr. Wu is having a crisis of conscience and is refusing to sell the guy any more smack for fear it will kill him, while the guy pleads with him.
It's about a guy trying to get in touch with his drug dealer. The narrator mentions that "Katy tried, I was halfway crucified." Katy, in this case, is a drug that almost killed him (most likely heroin.) Dr. Wu is the nickname of the the narrator's dealer, but at the time of the song, Dr. Wu is having a crisis of conscience and is refusing to sell the guy any more smack for fear it will kill him, while the guy pleads with him.