You should watch the movie its from. Fantastic. He goes insane and thinks he is a vampire. Its called "Vampire's Kiss." Probably his best work, hands down.
I can relate to this. Every fucking asshole does this to me. Most of it goes something like this.
some douche bag: "did you draw that?"
me: "yus"
douche bag: "no you didn't".
me: "are you brain dead?"