Trouble with flatmate using my kitchen utensils!?

ok well im in a flat of 6, and theres just one guy who uses my stuff. he has not used any of my dishes, but he has used other flatmates dishes. he uses my cutlery, spatual, can opener..and leaves them lying around! i wash them, put them back, say nothing. but THIS was the last straw; today he had friends round and they decimated my drawer! all of it was left out, all had been used. he washed some, but some are left out. i REALLY Want to just shout at him to stop using it, but should i ask him nicely? i dont want to rock the boat. also, he did not even buy any cutlery for going to university like nothing! no knives, forks or spoons! what should i do?