Species: goobit
Goobits are small, parasitic organisms that attach to the penis of a host and proceed to milk them. They feed off the semen in order to survive/reproduce.
Goobits can modify the host in any way they see fit, i.e enlarging the testicles to up semen production. The particular changes are ultimately up to the artist.
They act like condoms and thus the tag living_condom is used in tandem.