Knitting for Teenagers

We added two new members to our family this week -- both teenage boys. They needed a place to stay and we happen to love them so here they are. I want to make them something... but what do you knit for teenage boys? The older one likes Harry Potter, but I'm not sure it's "cool" for a boy to wear an HP scarf (now a teen girl could totally get away with it)plus it's getting to be warm here (88 degrees yesterday). They did like the purple hedgehog and mentioned making a blue one so it'd look like Sonic the Hedgehog (it's a drive-in, fast food place in parts of the U.S.). A new group of people to knit for.... hmmmm.....