Australian actor Heath Ledger is so excited he's playing THE JOKER in upcoming Batman film THE DARK KNIGHT, he's been preparing the role "like a lunatic for months". Ledger is determined his portrayal will not be a poor imitation of Jack Nicholson's Joker in 1989's BATMAN. He says, "I've been bouncing around like a lunatic for months. "I definitely have a different take on him but I've yet to do a proper make-up run." And the 28-year-old admits he's been practicing the Joker's unique laugh: "I'd be lying if I said I haven't been (rehearsing it)."