Keep on knockin' but you can't come in

I am going to recount my morning for the loyal readers of 'Life in these parts' for 2 reasons. 1. maybe you will laugh and I can feel better through your giggle. 2. I am so angry I can barely type this so maybe it will help get it off my chest.

So I get to work this morning and as usual need to make a restroom stop, #2, enough said. I suppose you need a little idea of the porcelain choices at this point. I can to the boys bathroom or the 1 person, deadbolt locking 'faculty' bathroom. Well I perfer a deadbolt especially if I am giving up the home field advantage. So the latter it is.
Of course while in-progress someone tries to open the door unsuccessfully thanks to my friend the deadbolt. Here is where it gets unusual - a knock, I give a slight 'Yea'. Footsteps walking away.. (a minute or two later) A push on the door, deadbolt blocks, and a knock 'Yea' I say. Mind you this door cannot be locked from the outside without a key that, I thought, no one had so its not like someone purposefully sabotaged the room with an unattended lock.
Now I hear keys rattling, and I am thinking - "what the f##, nooo are you kinding me" sure as I breathing the deadbolt releases and the door opens. I am really in shock at this point and say " EXCUSE ME.. IT WAS LOCKED FOR A REASON." suprisingly no king's english. The door shuts, I finish up quickly and charge out the door to bitch slap the offender. Nothing. I have no clue who it was and it has totally ruined my day....

Un-Friggin'-believable