The basketball club of our city held an online popularity contest, where the winner would receive free tickets or something. My friend desperately wanted to win this competition, so I wrote a Delphi program that would record the mouse clicks it took to perform a single vote and then repeat them forever. All of our peers received a copy of the program and in a coordinated attack, we opened the site in our browsers, taught the program to vote and left it running until my friend rose to first place. Sadly, he ultimately lost the competition, because another fan was better at forging votes. He surpassed us with ease. I guess he just hammered the server with HTTP POST requests, something I had no clue of at the time. In the end, the number of votes on the first and second place were laughably off the charts.
Years later, when we were adults, my friend became friends with the owner of the club, who invited us to a game. There, my friend introduced me by telling him this story, which I had completely forgotten. The owner had a good laugh, but I think I blushed a little.