That's a great question—since so many people masturbate! The short answer is yes. Throughout the day, your hands pick up a lot of bacteria from touching stuff. When you masturbate, you can spread it to your vagina and get a bacterial or urinary tract infection. Both are curable with medication, but they can be really painful and/or itchy while you have them. So always be sure your hands are clean before you touch your genitals.

What you're feeling, Jessica, is arousal. When you get excited sexually—which can happen even from seeing a sexual image—your body pumps blood to your genitals. The blood enlarges your clitoris (the part of your vulva that can trigger an orgasm after prolonged stimulation). That "thumping" you feel is the blood pumping to your genitals. Getting aroused doesn't necessarily mean you'll have an orgasm. You're just having a normal physical reaction to those sexy scenes.

Everything on TV is so overly dramatic, isn't it? In real life, orgasms don't typically make you scream and break things. They feel great—but that's about it. A typical orgasm feels like a buildup of muscle tension followed by a release of that tension. It's kind of similar to the feeling you have when you're about to sneeze and then you do. So if what you felt was like that (and it felt good), then you probably had an orgasm. Congratulations!

It's no easier for lesbians to catch STDs than it is for straight girls. STDs can be transmitted through all sexual fluids— semen and vaginal secretions. So you're just as likely to catch a disease from another girl as you are from a guy. Using dental dams (latex that acts as a barrier between the mouth and vagina during oral sex) or condoms on fingers can reduce the risk. Also, if vibrators or other sex toys are used, STDs can be passed that way. So sex toys should always be washed with soap and warm water before and after use.