arib is less than thrilled about this, so I suggested a crossover where K-9 appears on Firefly:
Me: Maybe if they introduced K-9...
Ari: If they introduced K-9, Mal would shoot it. Then Jayne would use it as a footstool.
Me: Then the Doctor would rescue his faithful robot companion.
Ari: Right, and Jayne would keep shooting him until his regenerations ran out.
Me: And then the TARDIS would eat him.
Me: And then K-9 would stomp all over Jayne's butt.
Me: And Kaylee would pat K-9 on the head and give him a doggie treat.
Me: And then we'd have a new TV show where Kaylee and K9 roam the galaxy, with similar sounding names.
Me: We could call it, "Kaylee, K-9, and Company"
Ari: And Kaylee could clobber Sarah Jane with a wrench and steal her apartment.