Fallon told Jackman, "We are going to have a water war. Now, it's just like the card game War, but with water. So, if you lose a hand you get splashed in the face. We each have five cups of water. The first one to use all of his cups on the other guy wins and gets to water canon the loser... Lots of ways to get wet, but only one way to win."
The game saw both stars throwing glasses of water at each other, leaving the set soaking wet.