Some people think Robert De Niro and Al Pacino would be a kick to watch just reading a phone book. Well, bring on that phone book. Righteous Kill, a.k.a. The Al and Bob Show, is a cop flick with all the drama of Law and Order: AARP. This movie defines drag-ass. Pacino, 68, and De Niro, 65, play 30-year veterans of the NYPD in search of a serial killer who only shoots scum the courts set free. The killer leaves behind poems explaining why his motives are — cue title — righteous. Hey, maybe a cop is doing it? Maybe it’s Al or Bob? I only wish Russell Gewirtz had cribbed more from his solid script for Inside Man instead of lifting from Dirty Harry, The Star Chamber and fill in your vigilante movie of choice. I also wish Jon Avnet had not been chosen to direct. Only five months ago, Avnet led Pacino to a career nadir in 88 Minutes. Was that not hint enough? Our only recourse in Righteous Kill is to get all up in the stargazing. “They’re like Lennon and McCartney,” says one admiring cop. De Niro and Pacino don’t really act here, they visit the movie like two Gullivers slumming with the Lilliputians. OK, it’s fun to watch them dropping f bombs and bad guys. But that one terrific, teasing scene they shared in Heat is worth more than two hours of watching them trade on our admiration instead of serving it.