You really never knew when you might run into another strange alien race. Even when travelling from planet to planet in the TARDIS, they popped up in the most unlikely places.
Here Donna and the Doctor were, floating in mid-space, when there was a knock on the TARDIS door.
The Doctor answered it, Donna right behind him. Outside were several small aliens, all identical.
“Greetings! We come in peas!”
“Don’t they mean peace?”
“Of course not. See their spaceships?”
Amazingly, the craft resembled pea pods.
Donna rolled her eyes. “You’re ‘avin’ me on!”
“No, really, they’re the original pod people.”