The Outside.
Lock them both in the trunk of the car for an hour, then open it up and see which one of them is happier to see you.
Because they didn't Lajka.
If the planes came from the outside.
Porcupines have pricks on the outside.
Spot. What do you call a dog who lays on a golf course Ruff. What do you call a dog who just got run over Rhody.
The Adhomineminal Snowman