Originally Posted by The Joker
You're almost right. When he's watching on TV the chaos Joker and Scarecrow have inflicted in their team up, he is impressed. He says "They do combine well for chaos. With more discipline they could take the city".
I think this would be the best way to show Joker, and Scarecrow, he's watching news reports of them after a breakout, or tapes of them on the news and he says those words.