Is it safe to use my phone while charging it? Does a charger leak electricity?
I don't know why someone downvoted the question since it's appropriate and useful.
In theory when you are charging the phone there's only about 5V involving from the power supply and the charger itself is build to avoid the mains reaching your phone.
That's the theory and in 99% of the cases it's correct. However, low quality chargers abound and not all of these have good insulation. In fact there have been casualties from people phoning in the bathtub with the charger attached.
So, if you are not excessively wet and the charger is well build the risk of shock is about the same of lifting a powered television set (i.e. substantially none)