How do i get my son to stop?

My 10 month old has seemed to pick up the Habit of slapping people in the face, and also slapping objects such as the spoon or his sippy cup out of my hands when i try to give them to him. he seems to think it is funny, but i want to try to stop this behavior. For a 10 month old he has got some power behind those slaps, and it really hurts when he slaps people in the face. he has caught me pretty good and i am tired of apologizing to shocked family members when my son does this. it is not a learned behavior-- i have never hit him and neither has my husband that's not how we plan on parenting but i don't know why he is doing it. any suggestions on how i can teach him that its not ok?