Antechinus

A small mouse-like Australian creature called antechinus literally f*ck themselves to death. The male stops eating and sleeping when mating season starts and he can mate with females for up to 14 hours at a time. He exhausts himself so thoroughly that his body starts to fall apart. His fur falls off. He bleeds internally. His immune system fails to fight off incoming infections, and he becomes riddled with gangrene. By the end of the mating season, physically disintegrating males may run around frantically searching for last mating opportunities.