Details of idea: Lets play it out as player get an magical item and allow to use it as a miniature of ourselves, to allow to explore the genital cavity of ourselves (if having a pussy), or some one else (if not having a pussy).
Probably could use as an interactive way to inspect if player got knocked up or way to avoid it (or help yourself to become fertilize) by clearing out sperms.
And probably would also be nice area to have some extra events like aftermath of slime sex that need to clean out before they make a lair inside yourself too.