A.C.
Ha! My son used to throw his sippy cup too! It used to drive me nuts. If he was upstairs, you could always tell when he was done by the big clunk as it hiT the hardwood floor. I think it must be a normal behavior for the age. When he did that, I used to let whatever it was (especially the cup) get "lost" in the house in the general vicinity he threw it. So when He wanted it again, it would be this big "well, YOU threw it away somewhere, YOU have to find it" party. Sometimes(when it was actually time to get a new cup) I would just throw it away never to be found again. For a while he would get upset, but eventually he took heed and started bringing it to the sink or putting it on a counter. If he threw something that could actually hurt something we would make him sit in "chair" for a minute-positively torture in his book! He's 5 now and is actually pretty good about putting his stuff away(to keep it together and lose things) and not tossing stuff accross the room. So I wouldn't worry- I think it is just and age appropriate thing for boys and they are just discovering thier hand/eye coordination.