Another suggestion, but one that may be unpopular:
Let me preface this with the fact the following does not particularly interest me but I think it may be a decent match for the games themes as this sometimes shows up in other media with an exhibitionism core theme.
Low Watersports - In so far as the player character urinates - not the other examples of that fetish.
Some of the ways I was thinking this could work is:
In one of the modes the character needs to complete a risky objective but the stress / heath bar does not regenerate over time. Choosing to urinate (a once per level action) instead of masturbate would quickly restore the characters stress / health bar and maybe allow the level to be beaten.
On non objective based levels as the characters stress / health bar is diminished the characters bladder fills up (functionally the same as the masturbation bar - can only use it for extra score once a minimum amount has been filled).
Choosing to do so is a non interruptible action that gives increased score normally along with a bonus multiplier depending on how exposed the character is - however NPC will detect a urinating character immediately if spotted (compared to the varying degrees of nudity causing varying amounts of detection rate (AKA risk vs Reward - more effort and risk required for a higher reward, as in a higher score).
In addition perhaps limiting the option to perform the action to when the character is squatting / crawling would make more sense and also forgetting to remove the character underwear / some over clothing before performing the action would have negative repercussions like a negative score instead of a positive one or treated as detected / fail state if the stress / health bar is two low as possible examples.