Doctor Who Season 1 Episode 4

(Dr. Sato and The Doctor are examining the pig-alien)
Dr. Sato: I just assumed that's what aliens looked like. But you're saying it's an ordinary pig. From Earth.
The Doctor: More like a mermaid. Victorian showman used to draw the crowds by taking the skull of a cat, gluing it to a fish and calling it a mermaid. Now, someone's taken a pig, opened up its brain, stuck bits on and they've strapped it in that ship, made it dive-bomb. It must have been terrified. They've taken this animal and turned it into a joke.
Dr. Sato: So, it's a fake. A pretend, like the mermaid. But the technology augmenting its brain… it's like nothing on Earth. It's alien. Aliens are faking aliens. Why would they do that? Doctor?
(Dr. Sato turns round and the Doctor has disappeared)