How can I convince my dad to let me get life sized cardboard cutouts of the Twilight characters?
Although I think this is a waste of money, you can go up to your dad and say “Dad, I’m pretty sure you had obsessions when you were a kid, so I’m sure you’ll understand why I want to get this”. If your dad still doesn’t let you, tell him that you’ll earn money for it by yourself to show how “mature” you’re being.