This Title / Question is hilarious in itself, as no one wants to crack his phone screen or destroy it, however the answer to this question is important in a sense that by knowing the methods of cracking or breaking a phone screen you can actually avoid them, especially when you have an iPhone 5S, Samsung Galaxy S4 or Note 3 along your side.
Here are some of the ways to crack a phone screen:
Sit on your phone
You can surely crack your phone screen simply by sitting on it. Smartphone screens are delicate in nature and even a normal pressure at the right spot is more than enough to crack its screen.
Throw it away
If the above method is not able to get the job done for you then this is surely going to get it right. By simply throwing your phone a few meters away you can surely crack or break your Smartphone screen, especially when it is on the floor. Throw it on the road, floor or from anywhere, this is going to get the job done right.
Keep on dropping it
First few phone drops might not be that effective, but if you continue to do that then this is surely going to crack your phone screen. Just drop it on the floor, on concrete, from your bed, from your dinner table etc and you will surely be able to crack or even break your phone screen.
The main reason for explaining the methods of cracking a phone screen is to tell you to avoid these things at all cost, as they might not only crack or damage your phone screen, but they might also damage other parts of your phone too. So avoid doing all that if you are willing to keep your phone in a long run, as replacing a cracked LCD screen alone costs you a fortune! But if you still managed to do so, then you can sell that cracked or damaged LCD screen to recycling companies, as they almost always pay good prices for broken phone screens (only if you have them in bulk).