Umamusume drawn in a chibi deformed style with a tanuki-style raccoon tail.
This trend was started by an art of "Shonbori Rudolf" (Feeling-Down Rudolf) drawn by Deon (post #5635540). It eventually turned into something like a microcosm of Umamusume, Horse Racing in general and general Internet memery. A lot of the content consists of short videos with limited animation, usually with the character flailing their limbs on their back (the "Tantrum" animation) or imitating the Komaru dance.
Much of the content depict the horse girls with exaggerated personalities and traits, or warped personalities (i.e. Special Week turning into a deadbeat father with gambling issues, squandering her daughter Buena Vista's earnings in failed bets). They aren't limited to the official characters, unmade or not and those original characters can be surprisingly well fleshed out for what should be glorified shitposts (The Tanuki versions of Melody Lane, Titleholder, Efforia and later, Shahryar, Uberleben, Equinox, Do Deuce, and many contemporary "fillies" all have distinct set personalities, traits and even storylines dedicated to them).