"In Episode 2F09..."
Anyhow, in the episode, the Riddler has Detective Yin running around Gotham answering riddles so as to defuse bombs that he's set. Naturally, Batman is helping her. About halway through the episode, Yin is standing in front of an organ in a concert hall.
She plays a D, and a piano falls from the ceiling. Batman tells her "Your other left." She then plays a G (actually, it shows her playing an A, but the tone produced is a G) and the bomb is defused.
So what's the point of my rambling? We're never told what the riddle was. The right answer was either G or A (take your pick). Yin apparently thought D was a good answer, but "Your other left" was enough to help her pick the correct key (and a higher note, no less) on her next try.
Given that information, does anyone have an idea what the riddle could have been? Or is it more likely that the show has no actual riddle in mind at all, but just wanted a scene with a falling piano? I expect it's the latter, but I like my Riddler stories to have good, actual riddles, and I have a nagging hope that this was one.