Zack Greenburg: [Zack meets his future son, Mack, who has time-travelled back because he needs Zack's help] So, do you want to take a shot at explaining this?
Mack Greenburg: OK. Yesterday, I borrowed something from my Dad. That's you. A certain family heirloom. But then I lost it, and if you find out, I'm grounded for life. So I came back into the past to find a replacement before you get back from work. The problem is, I need your help to pull this off.
Zack Greenburg: So this is the plan: You want me to help you replace an heirloom so that I won't find out that you lost it. You don't see the flaw here?
Mack Greenburg: It's OK. You won't remember. Look, future science has proven that at 13, your imagination is at its peak. But by the time you're 18, your brain cells start to deteriorate. And by the time you're 38, well, even if you do remember, your imagination is so fried, it won't even let you believe it.
Zack Greenburg: So, in 25 years, I'm fried.
Mack Greenburg: It's sad, but convenient.
