Help me s_d 2.0, you're my only hope!
I had this comic years and years ago, and it's disappeared since then. Scans?
It was an Alan Davis era Batman or Detective Comics. It had Batman & Robin going to Commissioner Gordon's office to find Catwoman (in the purple dress/green cape costume) lying on her stomach on his sofa and purring. From there somehow it's Batman and Catwoman going after Joker, and Joker shoots Selina with some kind of Comix Ray that makes her a killer kitty. Bats snaps her out of it, but she is Not. Pleased. with Joker.
And yes, mysteryfangirl and scottyquick's recent Bat/Cat posts are what reminded me of it :-)