A thin flexible disk, usually made of rubber, that is stuck up in a woman's pussy so that it covers the cervix and keeps the boyfriend's sperm from gettin' to her eggs when he cums inside her, thereby keeping her from gettin' knocked up.
My girl forgot her diaphragm so I had to pull out and cum on her tummy (ass-crack, back, whatever).
to play an online role playing game (specifically Everquest) while wearing a diaper, in order to not have to leave the computer screen to use the bathroom.