My thoughts...
Some babies hate sippy cups and will never use them. My sister got frustrated at 7 months because her gums hurt from teething, she picked up my regular cup before I could stop her, put it to her mouth, drank the milk out of it and never would take a bottle after that. Just try the regular cup, sippys aren't a necessity.
Another thought is he doesn't know he's supposed to hold it and drink from it, show him at the same time he's drinking how you drink from your cup. Modeling is how babies and toddlers learn how to eat, drink, go potty, etc. And it takes time, they don't get it until they get it.
A third thought is he wants to see Mommy jump to get the sippy as it hits the floor, it's a game and you play it. Either keep the sippy once he throws it and don't give it back to him until the next mealtime or get a a strap that attaches his sippy cup (or bottle or paci or toy) to his high chair, car seat, stroller, a shopping cart or his fave ride-on toy to keep them from hitting the floor. Game over. I just purchased some of these Sippy Secure Straps in several different colors for a couple of moms i know...wish I'd known about them with my little guy, he perfected throwing to an art ; )
http://www.sippystuff.com/sippy_strap/