I know that none of you squeeze your pimples, right? But if, hypothetically, you did, you'd be dislodging comedones — that gunk that oozes out of your blackheads and whiteheads. Comedones are little plugs of debris that stop up and irritate your hair follicle, causing a pimple, and they're usually a mixture of sebum and dead skin cells. A blackhead is an open comedone, and a whitehead or pustule is a closed comedone. Sort of a gross lesson, but good to know, right?