Ventilation shaft. You feel the warm air blow out of the HVAC units you can't see. "It's quite warm in here, isn't it?"
"Maybe we shouldn't be here, maybe it's illegal, but eh who cares, i read the rules of the school but didn't find anything about it."
"Honestly what did you expect to find in here? A rubber band to shoot at the teacher? Or do you just like the warmt in here? Either way, it might break under our weight-"
By 
