coconut crab
A large terrestrial hermit crab (Birgus latro) known for climbing coconut trees.
The coconut crab is known for cracking open and eating coconuts.
horribly drawn animated TV show
Only with reading ヤシガニ
Slang used in anime/manga fandom, derived from the reading ヤシガニ and the cross-reference 作画崩壊 (animation quality collapse).
See also: 作画崩壊
That anime's art is so bad it's being called a 'coconut crab'.
Katakana spelling is common for this animal name; usually written in kana.
Kanji spelling is rare; the word is usually written in kana.
The animal name combines 椰子 “coconut palm” and 蟹 “crab.” The animation slang sense arose from the notoriously poorly animated Lost Universe episode 「ヤシガニ屠る」 and came to denote severe animation-quality collapse.