Who Spayed Roger Rabbit?

(My parents have a rabbit named Roger. When they went away for a month’s holiday, they left him with my sister who put him in with her rabbits. A few days after they get back, they notice Roger acting oddly; not long after. they find that he’s now got a litter of kits. Mum is showing them to me.)

Mum: “He goes to your sister’s a perfectly happy Roger, and she sends him back as Rog-ette.”