Every rider knows what it feels like to ride a spooky horse. Or perhaps you have a “bomb proof” horse, except when it spots its bête noire, perhaps a pile of leaves that weren’t there yesterday or a particularly terrifying orange tractor.

Horses spook for myriad known and expected, as well as equally unknown and unexpected. reasons. They are, after all, prey animals with a strong flight response.

But if you’re an Olympic show jumping equestrian you might reasonably expect that if you’ve reached the top of the sport, your mount should be, shall we say, immune to spooky jumps?

No so at this summer’s Olympic Games in Tokyo where obstacle No. 10 on the show jumping course became what is known as the “bogey” fence. The culprit specifically was a life-size crouching statue of a sumo wrestler at the base of the vertical.

Sumo wrestlers are known for their body mass and for wearing only a mawashi, or loincloth, to cover their privates. Turns out that sumo wrestlers are not the preferred teammate for equines. Several horses balked, spooked, or out-and-out refused to jump No 10.

(FEI/Christophe Taniére)

“As you come around, you see a big guy’s [butt],” British equestrian Harry Charles told NBC News, who covered the event.

Ireland’s Cian O’Connor also remarked wryly, “There’s a lot to look at.”

The concept of a bogey fence is nothing new to show jumping. One of the most notoriously difficult obstacles was the innocuous-looking bicycle jump at Spruce Meadows. The bicycle fence proved to be the undoing of so many horses that several riders admitted to building their own replica at home to practice over.

In Tokyo, after seeing other riders having difficulties with the sumo dude, others who went later in the field made sure to trot their horses past the fence for a good glimpse before starting the course.

Regardless of the ability of world-class riders to overcome a bogey fence, the offending sumo wrestler jump and a thick patch of cherry trees (that were also blamed for causing horses to spook) was removed prior to the team event. According to course designer Santiago Varela, he planned on removing them anyway before the riders expressed their concerns.

But the Olympics are all about sportsmanship and as Britain’s Scott Brash declared of the sumo fence sitter, “You expect it in the Olympic Games… You know it’s going to be decorative. And it’s beautiful… That’s what makes it a championship. If it was just plain old jumps, it’d be just like any other week.”