Joker taps on the mic in Sharp’s office and leans against his chair. The intercom eerily chimes around Arkham Island, he laughed hysterically and spoke with a distorted voice that was definitely recognizable through the speakers:

"Good evening, residents of Joker Asylum! Some of our... crazier guests have crashed the party early. And when I say crazy, I mean real psychos. Word of warning! If anyone sees a dribbling maniac barking at the moon or maybe just purring like a kitten, do your civic duty. Walk up to them, put your arm around them, show them that you care before you wring their necks! HAHAHA!"