Dick is so great in this. The "I'm wearing a mask" line is fantastic, particularly in combo with the facial expression, and I love that he's a hundred times more furious about Harley in the Babsgirl suit than Babs herself.
It's six kinds of hilarious that Harley and Ivy just happen to have an original recipe Batgirl suit hanging around for play, though. Because, you know, that legacy needed to be gayer. XD