I wouldn't recommend spanking, mean mommy, or cold water. You have to remember that these are children who are brand new to the world and the ways of life and they need to be taught every Single thing by you, whom they trust. You have to nurture them and give them comfort and encouragement. They are counting on you to support them in their journey through life. Treat them the way you would expect to be treated if you were an unknowing individual. Fighting back or punishing them with these negative methods won't inspire them to thrive, it will only cause them fear, produce trust issues, and above all leave them confused, disappointed, and feeling misunderstood and abandoned. My parents used negative methods with me and it only left me feeling unloved and traumatized causing huge problems for me in my adult life. Just remember: children don't know what you know and they count on you to guide them, be loving, supportive, patient, and good teachers. Give them the tools they deserve in order to figure out this thing we call life and be the best version of themselves that they can possibly be.