Help! My 20 month old keeps throwing things on the floor in a violent way - food, drinks, toys, anything. I have tried saying 'no' (getting down to her level and being stern) and have tried ignoring it and taking the item away but she still does it and now she has a cheeky smile on her face when I tell her off!!! I'm fed up of wiping up spilt milk and bits of finger food. I'm scared she thinks I'm a push-over. Any tips?