For preventing stds use a condom birth control or abstinence
A lot lower risk of getting serveral differnt types of cancer to insure she isnt caught cheating and punishment to follow if she was drug tested at work, or at school, to prevent her from going into heavy depression later in life
Omg are you ok? if you do feel that way, think of alternatives that might prevent you. for example, maybe play around with an eraser or make knots.
do stuff you enjoy as well :)