He's not naughty - he's a baby

As your baby starts asserting himself, you may be surprised by some of his behaviour. He may know what "no" means yet still do something forbidden over and over again, all the time looking over his shoulder to see how you'll react. Punishments and anger do little good at this age, although distracting him often works. He can't yet "behave" as he's too busy experimenting. Try suggesting something he can do, like "give me that, please" or offering a favourite toy. Praising things your baby does that you do like makes it more likely he will do them again. Saving the "no" for genuinely dangerous activities gives it more power - he will know you mean it!