I heard that as well, I was going to mention it but you beat me!! I actually didnt see it on the show, I heard about it from my wife and we decided to check it out. We didnt see it, if you remember the exact let me know as we DRV'd the show.
BTW- her voice is deep for a girl, is there something I didnt pick up on that I should have?
and now a dancing corn cob
It was season 3 episode 5, "Tick, Tock Biological Clock". As far as the deep voice goes, as far as I know she's always been a girl.