OK Stupid Question...?

I'm becoming a freshman and will be starting High School next year. Today I just found out about a prank that all of the Seniors pull on the Freshman the first couple weeks of school. Well ya know the pieces of fabric that hang down from your backpack straps? The ones you use to make the straps smaller or larger? During lunch we have to leave our backpacks outside of the lunchrooom and while we're eating, they mix them up and tie those pieces of fabrics together. I know it sounds stupid but they're really hard to undo and once we're dismissed we have 3 minutes to get to our next cl. They tie them super tight so that its almost impossible to untie. We end up being late for cl and get in alot of trouble but they dont. Crappy way to start high school huh? Well do you have any idea how i can Prank Proof my back pack? LOL THANKS!