I was going to tell you why my door currently looks like this, but then I decided it would be more fun for you to guess! Post your guesses and I'll tell you the answer later!
ANSWER: Wow- you guys are really creative! Nobody came close to the real answer, but your ideas were extremely entertaining- especially the food slot (I love it!) I should tell you that this is how my door looks when the doorknob is removed! The reason they needed to remove it is really strange. My lock has always been a bit stubborn- when I unlock my door, it can be a little difficult to extract the key. My theory (and this is unconfirmed, although the maintenance man who fixed it agreed) is that the custodial staff got tired of getting their keys stuck and thought some good old-fashioned WD40 would loosen it up nicely. However, they used waaaayyy too much. The doorknob was greasy and when you put a key in the lock it came out covered in black grease! Not knowing what else to do, I called the maintenance people to fix it. They had to take it back to the key shop, clean it out (with more WD40), and dry it.