The Joker loves a good laugh. And a good party. There are several comic stories and written accounts of the Joker deciding that a party was called for, no matter the occasion. In one series of written stories tied to the 1989 Batman movie, he picks a random date as Batman's birthday and then proceeds to spend the night tormenting him, for example.
In this case, the Clown Prince of Crime decides to throw himself a birthday party. As a present to himself, he sends his henchmen out to kidnaps notable Gothamites who've interfered in his schemes, at one time or another.
Unfortunately for Selena Kyle, this includes Catwoman.
This story was set in the early eighties, a time when Catwoman was far from the ass-kicking martial artist / thief she would eventually become. No, this Catwoman was, for better or worse, still very much in damsel-in-distress mode.
The Joker ties his various acquisitions to giant explosive candles in front of a crowd of thousands of people lured to a stadium for a free bakery show (the eighties were an odd time for comics); Batman arrives to be the final 'candle' but, as always, outsmarts the Joker and frees not only Catwoman but the other kidnap victims.
That wouldn't fly for today's Catwoman...