be (a fine) one to talk

To be guilty of the same thing one has just criticized. A: "Kathy never pays attention in class." B: "You're one to talk! Just today I saw you reading a magazine during the lecture." Look, I know I'm a fine one to talk, given the fact that I dropped out of high school, but I'm telling you that you really need to take your studies seriously! He's a fine one to talk! He's always late to work, so why is he punishing me for being late one time?