The greatest practical joke of ALL TIME!

When I was a boy (and DEEP into my adulthood), I was quite the prankster. I was actually good at it, no, I would say I EXCELLED at it. I spent many hours thinking about and planning the perfect prank on the perfect person. I could have held weekend seminars on how to pull a great prank. I could have done a late night infomercial selling a 20 minute DVD outlining the key components of laying solid ground work and building a foundation for a strong prank. But I didn't and that ship has sailed. I have long since retired from that field and have lost the critical edge so necessary for good pranks.
There was the time we tricked my HS Spanish teacher into believing a buddy of mine fell out a second story window (I am thankful she did not have an ACTUAL stroke, although momentarily I thought she might), or when as teenagers we would take the universal television remote control, the one the cable company gave everyone when they installed cable in your home, at night around the neighborhood and point the remote in people's windows and turn the channel or turn the TV off and on while they were watching it (the efforts people went through to "fix" their broken cable box was hilarious), or the time we filled a 55 gallon trash can and leaned against the door of one of the guys in my dorm (after a late night knock, he opened his door only to be met my 55 gallons of water flooding the floor of his dorm room). These are all classics (although somewhat mean-spirited at time, thus my early retirement from the industry all together), but my question is - what is your greatest prank of all time? What is something you did (or had done to you) that will remain in your mind for many years and always gives you a chuckle when you think about it?
I want to hear what you got! I am searching for the greatest practical joke of ALL TIME! Do you qualify?