Awkward Objectives
Being embarrassed is one thing teenagers despise, but they enjoy watching their friends being embarrassed. Add a few objectives to the list that are sure to embarrass someone and have a teammate videotape or photograph the act. Enter a toy shop and have a male teammate yell: "Oh my gosh it's a Barbie!" or ask the clerk if they still stock My Little Pony. Dance the Macarena or the chicken dance in a crowded park. Serenade a stranger walking by or have a slow-motion kung-fu fight in the mall.
Collecting Things
As evidence that the team went to the location specified in the list, have the teenagers collect something to show as proof. Enter the town hall and ask for a stamp or a pamphlet. Keep the receipt for the bubble blower they had to buy at the dollar store. Ask someone of the opposite sex to write their phone number on a napkin. Make one of the tasks collecting as many soda bottle caps of a particular brand as they can find throughout the hunt. The team with the most bottle caps gets bonus points.
Food Challenges
If it's a longer scavenger hunt, some people might get hungry. Include on the list a quick lunch stop, with a twist. One idea is to order a hamburger from a fast food chain but without the bun. Convince a stranger to let you have a taste of his food. See how many marshmallows one teammate can put into his mouth.
Team Activities
Include the entire team in the scavenger hunt by having group activities. Photograph each activity as proof that you did it. For example, get the entire team inside a pet store, and get extra points if one teammate is holding an animal. Build a human pyramid. Fit as many teammates as possible into a phone booth. Take a photo of the entire team jumping and another one of the entire team climbing a tree.