I totally get that. owo Rather weird one, even I'm kinda iffy about it. Buuut, I do have an idea perhaps that you may find quite nice for an RP situation. :3
Gotta do a tad more planning for it of course. But! I'm absolutely certain you'd enjoy it. >w<
The goo pumps into you faster and faster, stretching your belly to ridiculous sizes, until the slime forces its way up your throat and into your mouth, bulging your cheeks and poking out between your jaws.
The goo coming out of your mouth forms into a tentacle that thickens and thickens, stretching your neck and jaw. The goo coming up your throat also fills your sinuses and oozes out your nostrils. The slime entering your rear also intensifies and shows no sign of running out.
Gotta do a tad more planning for it of course. But! I'm absolutely certain you'd enjoy it. >w<