''I enjoyed working with Billy Bob Thornton in Monster's Ball, in the scene where he smacks me around in the bathroom,'' says the 27-year-old Aussie, speaking of the 2001 film in which the actors portrayed father-and-son prison guards. ''I enjoyed that, because he really hit me, you know? I like when people take it to that point. I remember it being an adrenaline rush.'' Ledger who next stars in the junkie romance Candy, which premiered at last month's Toronto film festival reveals that Thornton did say he was sorry for the onscreen ass-kicking, but ''he didn't write a formal apology. We just laughed and joked about it.''