For her: Anything cropped, neon, or off-the-shoulder will do. You could also spring for a t-shirt with The Max logo or a Bayside High sweatshirt. Don't forget to spray your fringe up!
For him: A blonde wig is a must, along with a collared shirt (don't forget you're preppy!), baggy jeans, and old-school high-tops. A giant fake mobile phone will really complete the look.