Black Snek TF! (Patreon)

This guy meets an alien symbiote, but not the way he expected... and gets turned into its chastity slave host! With one big bite, the snake will close its jaws around the poor victim, enclosing his body until its tiny head bites his crotch tightly and stays that way. It will use its host to move around and protect itself, and force it to grow in the meantime.

(His friends found him, but they didn't recognize him and left the planet scared of that huge monster. There wasn't much left of him to mind about that, tho...)

HQ and whole strip: https://www.dropbox.com/sh/7wt14ui7j9v9bmz/AABFcaupBOmEkuMjOmavko0Sa?dl=0