One Perfect Moment - The Joker meets his match!
This perfect moment is from Impulse #50
Bart is on the hunt for practical jokes he can use on Superboy and Robin. The warehouse for mail order joke company is in Gotham, so he pops along to see what he can find, but discovers that the Joker has taken the place over and Batman is lurking outside in an uneasy standoff.
The whole story is a classic, but I've always loved this little exchange. Through a series of events, the Joker has manoeuvred Impulse into running around doing all sorts of silly things just for giggles (You can see the results in the first few panels), until even the Joker realises he might have finally met his match;