The last-place Chinese team was apparently the gold-medal favourite, but, according to the BBC, "a mystery spectator -- dressed in traditional Greek knickerbockers with the name of an internet betting company scrawled on his bare chest -- jumped on to one of the boards not being used for competition and bombed into the pool."
After the competition was delayed and the dorkwad was hauled off, the divers proceeded to botch their last dives. The U.S. team had a terrible landing, one of the Russians touched the board on the way down -- generating a very low score -- and one of the Chinese divers (no one seems to know who's who) hit the water on his back, generating the even lower score of zero. Leaving the expected winners in last place and the actual winners surprised.
All because some web site tried to spam the Olympics with a cannonball-diving fuckwit.