How can I be sexy around a guy?

I have a HUGE crush on this guy at my school. But I always act like a dork in front of him. Like, I start talking about soup labels and how to work iTunes and stuff like that. Now, this guy is really hot. He knows Ive had a crush on him for a while; its been 3 or 4 years. So, any advice on how to not be a dork around him?