Blimey I don;t really tell ds (14 months) off for that! I keep telling off for dangerous and really unacceptable things, otherwise I wold be stern and grumpy Mum all day!!!
I just say "if you don;t want any more say no more Mummy, don;t throw it on the floor" hoping that eventually the message will kick in!! When he chucks his drink on the floor, I ignore it, pick it up and put it out for reach until he asks for it again.
I mainly tell him off for touching the oven and opening it, touching & throwing things down the toilet, and chewing outdoor shoes.
The best way to deal with them at nappy change / dressing undressing time is to involve them ime.
Ds is much keener now he "helps" put his clothes on, and when we take off the dirty ones he puts them in the laundry basket all by himslef...he thinks he's ace!!!!
I also use pull ups which I am getting him to put his feet into, and then I pull them up.
Ok I still have to be stern about really pooey nappies, cos I think you have to do them lying down, I just try distraction with a song or a toy.