To Slimer, this squishy meat bag was just a moving fleshlight. No need to care for his wants, his desires. Only Slimers.
Eventually, Slimer completely mutates into a 6-foot penis; no body, just a cock. Also, they're doing anal, which leaves "Sam's asshole ... as large as his head." By this point, Sam is rapidly losing blood and begging for death, which is silly, because Slimer would probably end up fucking him in the afterlife, too.
Meanwhile, Janet, a worker at Ghostbusters Headquarters who did not exist before this thing was written, has sex with a mysterious woman who just showed up and got naked. This is barely connected to the Sam/Slimer tale, and it almost feels like a whole other story tacked on by the author to satisfy some imaginary word count requirement. Soon the two girls are joined by Steve from accounting, who "was actually named Logan. He preferred Wolverine, however." The woman then reveals herself as Jean Grey. What we're saying is that erotic Internet fan fiction is a magical world where anything is possible.
Note to Editor: Everyone on the layout team is refusing to replace his claws with dildos.
So anyway, now the X-Men are involved in this mess. Then Jean Grey shits into Janet's mouth, Janet eats it, Wolverine literally fills the entire room with shit, and the three suffocate and drown, neatly tying up this story's one and only loose end.