you walk in your last period classroom (the room you float into with your cart)...that classroom's teacher is absent and has a sub...he's also asked you NOT to turn off his computer (working with a dying battery somewhere inside)...
...so you see it's turned OFF! And (thankfully with no students in the room yet so you don't have to explain) you say to yourself...MMM, you in some trouble, sub--I know where you've been!!