Proper way to discipline pet rats?

Hey I have two pet female rats whom I very much love and adore. They come to me when I need them to, they love to crawl on my shoulder, and they are pretty much great rats. I am in a General Psych course in college and we were learning about how rats learn extremely quickly through punishment and reward (aka the Skinner Box. The skinner box is a contraption that psychologists would use and every time the rat did a desirable behavior, food would go into the cage, and every time it produced an undesirable behavior, the floor below it would give the rat a little shock. Something similar to an underground fence collar for dogs.) Well anyway, rats are smart and can learn very quickly through this method. So having this in mind, I would like the proper way to "shock" or discipline my rat in a way that is not hurting them, but just startling them so they know not to do it again. Because of the changing weather, it is warmer out and I have my windows open, and my rats will climb up to the window and climb up the screen. Of course this is very dangerous considering I am on the second story of my building. Right now I try to speak loud and mean and pick them up and tap them on the head a little so they know not to do that. It seems like yelling at them is ineffective, and I am not all too sure about how effective the taps on the head are. My one girl, Elton, it seems to work for her. But my other girl, Lucy, it seems not to be as effective. Does anyone have good advice? Spray bottles? Anything? What should I use just so they know not to repeat that behavior?