A fact that most may not know about slugs. This happens sometimes when the slug can't dissconnect itself from another slug, so that a delibrate amputating of the penis will take place. Basically, it's a major factor that makes slugs he/she's or a more appropriate term: hermaphrodite.
Q. What happens in the world of apophallation of slugs?
Apophallation is a tactic occasionally used by hermaphroditic terrestrial gastropods during copulation. The mating rituals of some of these species involve two specimens wrapping their penises into a spiral and exchanging semen between them. However, once mating is complete, it is sometimes impossible for the couple to separate, thus requiring them to amputate one of the penises by chewing it off.