On the disc 3, during the Badge of Gayness and Mr. Hankey's Christmas
Classics, on the commentary, Trey and Matt spoke about Mary Kay. They
said that she killed herself and they had a few shows left to do and
scrabbled around to make stories that wouldn't have any female
characters. Then they would grab anyone who was in the office to do
the female voices before they held any auditions. Also during Mr.
Hankey's Christmas Classics, if you look at the end of the last song,
South Park had a flash of Wendy, the Mayor, Lianne Cartman, etc. and
then a gathering of all the other women that Mary Kay has done. I
think some way that was their "tribute". I heard that there was "In
Memory of" on one of them but I've gone through every credits on the
3rd disc and couldn't find anything.