When a male or female feels uncomfortable having sex in someone else's house or apartment. They can only fornicate in listening distance of their parent(s).
Boy: "Hey baby, wanna come back to my apartment so we can have some alone time?"
Girl: "I'm not a huge fan of sleeping with you at your place, I would feel more comfortable with you pounding me in my parents guest room."
Boy: "Thats the room next to your parents?"
Girl: "I know" (wearing a very dirty smile)
Boy: "You definitely have security blanket sex syndrome, I should probably go look for someone else, but I think your hott so I'll be by in a little bit"