It's bad to let other people hear you have sex.
Drew and Anne are engaged and are being visited by Anne's parents for the weekend.
Drew wants to have sex with Anne during her parents' visit.
Drew asks Anne's parents if they would mind picking up dinner if Drew pays, and Drew seduces Anne while they're away.
Drew convinces Anne that her parents won't be able to hear anything since the door is closed, and they have sex in their room as usual.
Anne's parents don't find out about the sex since they return from picking up dinner after it's over.
Anne's parents hear enough to be able to tell what is going on, and it makes the rest of the visit awkward.