If you were tuning into the BBC's coverage of The Open Championship this morning you would have heard Maureen Madill explain that Rory McIlroy's father Gerry put £100 on his his son winning The Open by the age of 25 at odds of 500/1 ten years ago.
He also persuaded three of his friends to place the same wager and wanted to put £400 quid on it originally but the bookies wouldn't allow it.
McIlroy is of course 25 now so we've no idea if the bet is still valid but still, it puts your dark horse wager into perspective.