Standardbred's at Greenwood racetrack when it was still around (still miss it btw. My track now is Flamboro but Greenwood was better and Woodbine sucks for harness). Anyways I digress.
Race was some kind of 2YO Fillies Ontario Sires Stakes and some clown(s) bet $30,000 to show on an undefeated trotter. I couldn't believe my eyes. Sure the horse looked good but it was after all, 2 YO trotting fillies who break stride more often than Ozzie and Sharon Osbourne swear.
The horse I liked for 2nd behind the big favorite was 50/1 (which of course is irrelevant since the favorite was like 1/10), but it only had $5 to show on it when I had bet it. So I put $100 to show myself on it. My hunch was that I would get back $105 on a $2.10 payout but it was worth a shot just in case the fave screwed up. Sure enough the favorite broke from the gate and continued breaking eventually pulling up. My horse was one of only 3 to stay on stride and finished 2nd. It paid $132 to show. So for my $100 show ticket I got back almost 7 dimes

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As for sports, last year I won on Shigeki Maruyama at 100-1 for $50.