I have three examples...
Cricklade College, Andover:
Many moons ago there was a tour of the college set up for the local secondary school children. Among the many exhibits put out on display in the biology department was a dissected rabbit stored in a tank of formaldehyde, its innards all neatly spread out and labeled. Placed with equal neatness and precision upon the tank was a small notice left by one of the college students. It read: "Bugs Bunny".

Southampton University:
Again many moons ago whilst I was wandering the darker, lower recesses of the student union building I happened to venture on a plaque marking one of the debating chambers... someone amended it to "Maths Debating Chamber".

The last one was in a hospital waiting room. Among the reading material present was a girly-type annual circa 1972 (it was probably a cheap knock off of Bunty) – inside the annual was a photo story. In one picture was a (suspiciously) cheery male lift attendant stood in a lift with a young girl. The original text read "Going down?" to which somebody added a cute little speech bubble from the girl saying "Yes please!" For some strange reason this has mentally scarred me and I still cannot go into any lift without quoting this.
( Templeton Blah, blah, blah..., Fri 4 May 2007, 18:38, Reply)