S10E5: Back to the Pilot
PAST BRIAN: Whoa, ass ahoy.
All right, look, there we are.
PAST BRIAN: Hey, Peter, it's 7:00 and you've still got your pants on.
What's the occasion?
Stop! Both of you! What the hell?
Who are you? We're you, from the future.
Oh, boy, this can't be good news. Who screwed up?
Take a wild guess.
What did I do? Well, nothing yet, but listen.
Whatever you do, you cannot tell your former self, that Brian, about 9/11.