I haven't seen this anywhere, and having had the idea I don't want to risk forgetting it. So I'm talking stuff like this https://e621.net/post/show/897540/2016-anthro-anus-belly_scales-bent_over-big_butt-b But maybe you could have the option to crank it up or down, and change the color. Maybe there could be a species, or it is just a rare thing that anyone could have. You could take the dna, enabling you to put it in other subjects. Perhaps their cum/fem cum could glow as well. Making the colors match could be optional, allowing the player to have any combination of them. As an offshoot, perhaps it could affect lactation. Affecting color and possibly flavor for both.
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