You should turn these moments into a learning opportunity so your child really won't do it again. It is important to teach your child some key words so that you can quickly stop him in his tracks before he could get hurt. You may need to do this several times. Your child is going for the electric outlet for the 100th time. Opt for something new.
Children learn at an early age to stay away from things that are hot.
Now, you are thinking, this approach won't work. It won't work the first time, but if you consistently use these phrases and remove your child, he will eventually get the message. Turn it around into a more helpful phrase. This toy is your sister's and this toy is yours. Food is to be eaten.