The racehorse Oguri Cap was a national favorite in Japan and would attract crowds whenever he raced. The gathered fans would chant his name repeatedly from the stands, with unusual emphasis on the first two syllables.
The above is referenced during S1E6 of the Umamusume anime, with the crowd cheering for Oguri in a food-eating contest. Fanart of Oguri tend to use this chant when Oguri is involved in a food contest. The meme has also 'mutated' further with "ooh-goo-ri ooh-goo-ri" being used as a character-specific onomatopoeia for when Oguri makes an appearance or when she is involved in her antics (eating lots of food, usually).
In written works, this chant is almost always repeated at least twice, and spelled as "オーグーリ" (ooguuri) with lengthened vowels on the first two syllables.
