How to make iPhone 4S battery swelling?

I want to know how to make a iPhone battery bulge ( swelling ). My friend said if we put the battery in water it will swell. Let me know the options to do it.

A swelling battery can come from 3 things. 1 an internal short (manufacture defect ) 2 being left in direct sunlight (letting it sit on your car dash all day in the summer heat ) 3. The battery being completly discharged ( dead) and freezing ( the less of a charge a battery has the higher its freezing point )