(Way) back when I was at Sheridan College, the custodial staff took great pains to scrape down and repaint the bathroom cubicle doors (the Board of Regents was due for an inspection/visit). This was taken as both an insult and a challenge by the creative types in the photography depsrtment. No sooner had the fresh paint dried than a very formal-looking notice was inked upon the door:

"The management wishes to apologize for the actions of an overly zealous former employee in eradicating the creative efforts of the student body. Please start over."