It hardly ever hurts in a tongue or ear. Nipples and genital piercings definitely are more painful. The procedure is quite simple, but the proper knowledge is what is most important. The area of skin to be pierced must be cleansed thoroughly with a medical skin disinfectant. Marking a precise spot for the piercing itself is very important for health reasons and for the overall look.
Improper placement can cause unnecessary rejections.
The needle is then pulled through without any further discomfort. A gun should never be used for any body or facial piercing. Piercing guns are inaccurate, more painful and not as safe as properly sterilized needles. You are in good physical and personal health. You are at least the age of consent.