I would’ve thought that you were twins and thought that 8 hours of sleep meant for both of you together.

Not that I get 8 hours of sleep, mind you

How old are you in human years?

That’s because he wants to climb to Mars on his pile of money, and right now it’s not quite high enough

You need a key though, which only the landlord has

It’s all a misunderstanding : as they are French, they’re talking about cats!

I explain it by repeating what Google tells me.

They’re just going to throw a few more projects on the Google graveyard then

That’s easy : multitasking!
You do 2 tasks at the same time, and both tasks are “sleep for 4 hours”.
So after 4 hours you’ve slept for 4 hours twice! 8 hours!