S10E5: Back to the Pilot
Hey, wait a minute, Stewie. That's the spot!
That's where I buried my tennis ball!
Whoa, whoa, Brian, what are you doing? You can't dig it up here.
Just make a mental note of where you buried it,
and as soon as we're back in the present, you can dig it up then.
Because we can't risk doing anything that alters the past.
You know, I never got that.
I mean, wouldn't you want to alter the past?