How do you hide that you are not a virgin from your parents?

(1) Don't tell them.

(2) Don't be paranoid that they know or will find out. If you become paranoid, your five times more likely to inadvertently tell them.

(3) I really hope you were "safe" and go to the doctor's immediately (even if a friend takes you there instead of your parents) if you think you have an STD or unwanted pregnancy.

(4) Just remember that unless virgins have green ears and non-virgins have blue ears, your parents aren't exactly going to be able to tell just by looks.