It's like a, some years ago, there was a ridiculously unworthy horse entered in the Kentucky Derby, and it became a media darling b/c of the novelty. It had astronomically poor odds of winning, yet the day of the race, it was posted at 100:1, b/c people kept betting on it. Of course it came in dead last and seriously behind. But, as the announcers pointed out, the romanticism of such an utter Underdog Horse winning the Kentucky Derby was like something from the movies, and people couldn't resist it.

Any idea of the year or horse?

When you say 100:1, do you mean uk odds 100/1 or the reverse? As in, do you mean stake $1 to win $100 or stake $100 to win $1?