"Let's go back to your house," says Brooke. "I think I have an idea."
You and Brooke drive back to your house, and she leads you down into the basement. She sets the box down on top of the washing machine along the wall and slips on one of the rings. Finally she hands you the watch.
"Okay," you say. "Now that we're here, where are we going?"
"You've lived in this house for your whole life, right?" she asks, already aware of the answer.
You nod. "Yeah. So?"
"Well, I've always been sort of curious," she admits. "I want to see what you were like as a little kid, before we knew each other. Before I even lived here."
Brooke's words surprise you. That would be a LONG time ago. You are 23, and she is 21. Even though you've only really been an item for a few years, you first encountered each other in high school, when you were a junior and she was a freshman, and you know that her family had moved into town about sixteen years ago.
"Well, I guess we could do that," you finally say. "As long as we also go back to when you moved here, so I get to see what you were like."
"Sure," says Brooke.
"Alright, let's pick a nice round number to start with," you say, putting on the watch. "Exactly 20 years ago."
You push the button to stop time. Aside from the sudden silence, it's hard to tell by looking around you, because the basement is empty aside from the two of you, but when you look at your watch, both displays have frozen in place at 4:35:19 PM. "Hey, look at this," says Brooke, glancing up at the wall clock. "The second hand on the clock stopped moving. It works!"
A feeling of excitement begins to come over you. "Okay, let's see what happens when I adjust the time." You begin pushing the buttons on the watch until you have the year on the top display highlighted. You make a small jump at first, from 2015 back to 2014. Looking around you, not much has changed-- some subtle differences in the placement of items. So you make another small jump, back to 2013. This time, you and Brooke are immediately surprised and amused, and rightfully so-- your 21-year-old self and her 19-year-old self have suddenly appeared on the sofa, frozen in place, in the process of making out. "Oh, hey," you say, with a chuckle. "I remember that."
Now fully convinced that the watch really works, you keep going backward through the years, watching the basement change around you, and your frozen self and friends and family members occasionally appearing and disappearing, gradually becoming younger with each year further back. Around 2006, you notice the placement of the furniture in the basement shift dramatically. Around 1999, the drywall disappears from some of the walls, leaving the exposed studs. Finally you arrive in 1995, exactly twenty years earlier than you started.