A girl invites her boyfriend over for dinner with her parents. Since this is such a big event, the girl tells him that after dinner she wants to have sex with him for the first time.
The boy is ecstatic, but nervous because he's a virgin. He goes to the pharmacy to get some condoms. He tells the pharmacist his situation and asks for advice. The pharmacist tells him everything there is to know about sex. At the register, the pharmacist asks how many condoms he'd like to buy: a 3-pack or a 10-pack. The boy says he feels lucky and insists on the 10-pack.
That night, the boy shows up for dinner a little late. His girlfriend meets him at the door leads him straight to the dinner table where her parents are already seated. The boy sits down, quickly offers to say grace and bows his head. A minute passes, and the boy is still silent with his head down. Five minutes pass, and still no movement from the boy. Finally, after 10 minutes, the girlfriend leans over and whispers to the boy, "I had no idea you were this religious."
The boy turns and whispers back, "I had no idea your father was a pharmacist."