Where do they come up with these things?

R: Maggie have three legs!
K: Yup, Maggie has three legs.
R: Why? [Rudy has recently discovered the wonder of why and no.]
K: One was sick.
R: I not have three legs.
K: Nope.
R: I use-ta-have three legs.
K: Oh really?
R: Yes. [long pause] One fell off in my garage. [long pause] Crabby chomped it off. Now it's all gone in the garage.