A million is already a thousand thousands but we could go further. Make a billion a million millions and make a trillion a billion billions, etc. Imagine the numbers we'd find.
You could be saying things like a thousand million or even a hundred thousand million billion. You could say 999,999,999,999 as nine hundred ninety nine thousand nine hundred ninety nine million nine hundred ninety nine thousand nine hundred ninety nine if we weren't number cowards. If you're afraid of the sky then die in the dirt