Hosajack is a blue serpentine creature with markings on its body which resemble sperm cells. It has fin-like potrusions on its body and its tail ends with a lighter colored tip. It has two circles on its face resembling cheeks and is always seen with a toothy grin.
One of the proposed names for it during development was Hosajakir.
Hosajack is based on a sea snake or sea serpent with sperm cell characteristics. Hosajack also has some features that pertain to fish or cetaceans, the latter of which may reference sperm whales. The sperm-like markings on its body suggest that it may also draw inspiration from a condom, which, once used, may contain semen contaminated with bacteria or viruses, hence the Poison type. Its facial expression resembles that of somebody who is masturbating. Its serpentine body suggests it draws inspiration from Eels.
Hosajack is a combination of hose and jack (from jack off, which means to masturbate).