What's the best prank you were ever a part of?

I was an young E1 at my first duty station. I was outside a restricted area. Our fence had sensors which caused alarms. There were these little boxes the wires ran through (unbeknownst to me). My sup told me I had to conduct a VSV (voice sensor check). He told me I had to go to each box and yell into them. He had set this up with the alarm monitor and the rest of the guys in the area. So I go to the first box and say "rah", my sup yells "louder, say it louder!" "RAH!" I yell. He says "got it, next one". Fifty plus sensors later, everyone on my shift and a few non-security munitions guy all saw me yelling at a box that had no microphone. I was also given a garbage bag and told to run around the flight line to get an air sample. Finally, they told me to get the key to start the B52 to base op's (the key was a lever used to crank open a window). Yup, totally gullible. Truth be told, after 23 years, I may still do crap like this. Good times!

Pallet wrapped a guy's black 88 Monte Carlo during the summer. He needed a box cutter to get into his car.

While in Korea, I had a CO I was always playing pranks on. I would fill all his desk drawers with packing peanuts, or I would do other such pranks. He would prank me back as well. This was between the two of us and no one else in the unit was any wiser. It was fun and it broke the boredom. He was an awesome CO.