After some exhaustive research, and some mind-blowing revelations about the human reproductive system, I realized that the way I had draw the previous internal shot was totally wrong. I decided that it wasn't good enough, so I took the liberty to reenvision, and redraw the panel.
Now we have a more accurate depiction. Keep in mind that in this scene, Sharlene's body is facing us, and Marvin is behind her (so here we see the top of Sharlene's, and the bottom of Marvin's, respectively). The eruption now occurs inside the vagina itself, filling up the basin at the end of the canal. You'll notice the tip of the cervix (the round shape with the cute little belly button in the center) is peeking out, above the opening.
Marvin still had plenty to share, so I made sure to make this panel *extra juicy*. Now tell me what's more sexy than some sweet, sensual, comfortable, love-making... followed by painting the walls with a brand new color.
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Oh - and just a heads up. I might share this image on my Twitter. Seeing as that's where this whole debacle originated, I think I owe my followers there the finished fruit of my findings, at least in this case. I do, however, have another page update for my supporters tomorrow, and the finished page will be ready soon after that.
Thanks for your support! ❤