Check out this instructional prank video and learn how to perform this practical joke that will leave your friend puzzled! Learn how to lock your friend's backpack with this simple tutorial video. All you need is a zip-tie, and a good time to grab your friend's backpack at school. Perform this trick and your friend will not be able to open his backpack for his next class. Use this as inspiration for one of your April Fools Day pranks!