Leonard, Sheldon and others in “The Colonization Application”

Leonard

Why a turtle?

Sheldon

After much deliberation, we've determined that a turtle is the ideal pet. They don't shed fur. They don't make noise.

Amy

For Halloween, we can dress him as a cobble stone.

Sheldon

And, if he ever goes beserk, I know I can out run him. Coincidentally that's also why I chose you as a roommate.