Don't let your roommate bust your groove. Get the privacy you need for your extracurricular activities.
Step 1: Make a plan Talk about the issue before it becomes an issue. Have a frank discussion about what to do when one of you needs the room to yourself to entertain a guest.
Step 2: Use technology If you can give your roommate fair warning, or you're out and they're nowhere to be found, use text, e-mail, and social media to send the message you need a little privacy.
TIP: Be considerate. Don't give them the boot the night before finals or a big game.
Step 3: Put something outside If you're already in the room and your roommate is out, put something outside the door or on the doorknob that signals you need a few minutes with your "lab partner" to study some "anatomy."
Step 4: Decide on code word If you're both home and you want your roommate to clear out, use a predetermined code word. Just make sure it's not something that comes up regularly in conversation.
TIP: Give them a "thanks-for-getting-out-so-I-could-get-it-on" gift like beer or pizza if you've been a particularly demanding roommate.
Step 5: Find opportunities Get to know their schedule so you don't have to sexile them. When they're at an early morning class or at a late-night study group, you can get down and they'll be none the wiser.
Step 6: Be patient Sexile is tit for tat. When they need the room, remember to be patient. Maybe you can even use the time to do some actual studying!
FACT: In 2009, Tufts University instituted a rule prohibiting students from having sex in their dorm rooms while their roommate was home.