About 5 years back I was trading a Polish 2nd Division game In Play, watching the thing on some Polish TV station and moving odds. Just before half time all sorts of Polish customers started backing the home team to win, a grand at a time. The price collapsed everywhere else, I suspended betting thinking it was a definite fix. Anyway about half way through the second half it was still 0-0 and there was a scuffle between the players on the pitch where they started kicking the **** out of each other. Needless to say, if you're fixing a game you don't punch each other in the face, you tend to be a lot less competitive. So, with the price of the home team collapsed, I immediately jumped on the away team with 100 quid at 20/1 (if it's not a fix, then away team are massive value as they've been pushed out, because everyone thinks it's a fix). About three minutes later the away team run up the pitch and score a goal.
Boom, it's not a fix, £2k on the way, etc. Only about 2 minutes later there's a pitch invasion - about 100 fans run on the pitch and start tearing up the place. Match abandoned, all bets void - got my stake returned.
So aye, it turns out that the fix was not to do with the players - it was if the home team wasn't winning by a certain stage in the game, the fans would invade the pitch and all bookmakers would declare it a void, therefore every **** who had their money on the home team couldn't possibly lose.