A fort made from blankets or anything else in a shopping mall parking lot (covered or not) that's used for the purpose of having sex, making love, performing oral, and/or making cumsies.
Them: "Wow! Where have you guys been? You were supposed to meet us at the food court at 12:30! And why are your faces red?!"
Us: "Oh, you know, we were just hanging out in out mall fort and we lost track of time"