noun
coconut crab
A large terrestrial hermit crab (Birgus latro) known for climbing coconut trees.
ヤシガニはヤシの実を割って食べることで知られている。
The coconut crab is known for cracking open and eating coconuts.
noun
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
あのアニメ、作画がひどすぎてヤシガニって呼ばれてるよ。
That anime's art is so bad it's being called a 'coconut crab'.
作画崩壊 refers to a collapse in animation quality; ヤシガニ is a slang term for a show suffering from such a collapse, derived from the reading.
The animal name is a compound of 椰子 (yashi, 'coconut palm') and 蟹 (kani, 'crab'), referring to its habitat and appearance. The slang sense is a fandom coinage from the katakana reading ヤシガニ, associated with 作画崩壊 (animation quality collapse).