In order to put the universe back as we remember it, and get back to our reality, we have to find out the exact date, and the specific circumstances of how, where and when Young Biff got his hands on that sports almanac.
16 seconds sound clip from the Back to the Future Part II movie soundboard.
You can hear this line at 00:55:12.693 in the Blu-ray version of the movie.
Quote context
[...]
- Right. So we go back to the future, and we stop Biff from stealing the time machine.
- Bulletproof vest! Great flick! Great frigging flick! The guy is brilliant.
- Hey, what the hell's going... Hey! What the hell are you doing in here?
[...]