Detective Comics, Vol. 1 #869 (2010)

Batman: Imposters, Part 3: Laughter Out of Dead Bellies
After weeks of public inactivity, the Imposter Joker releases his Joker Juice at a town fair; the Guardian Bats gather to take on the Jokerz as the Imposter Batman throws a child from a rooftop.
Release Date: 2010