PROBLEM: Your bedroom sounds like high-school detention--silence, with maybe a few giggles.
Men love it when women moan, scream, and pant as if they've just finished a marathon. It makes it sound--to the flight attendants, anyway--as if we know what we're doing.
SOLUTION: Create chaos. If she's stifling her moans and groans, it's probably because she's afraid of waking the guards. So do anything you can to create a lot of background noise to make her feel relaxed--run the dishwasher, have sex in the shower, drop a CD. You can even sing a little: When you're giving her oral sex, hum along. The low vibrations from your vocal cords will feel incredible to her. Press firmly with your lips; the front of your mouth is where the tissue is densest.