Here's a bizarre tidbit of insane gamer logic for ya. A while ago, I decided to run Tom's Divine Fire scenario, and my players liked it and the characters they were playing enough that they wanted me to continue the story. I decided to have the survivors of the debacle at the secret Nazi complex join up with a Delta Green-esque branch of the military whose mission was to investigate and deal with supernatural threats on the battlefield, and sent them off to investigate a small town in the Hautes Vosges mountains where a critical supply line to the Franco-American allies was being disrupted for unknown reasons. Basically, the Nazis approached some Mi-Go that were mining in the area and negotiated for some advanced alien technologies, while simultaneously conducting research into creating their own CoC versions of horcruxes ("Apportion Ka" is the spell, I believe), a scenario that resulted in a bunch of disembodied Nazi brains taking control of a company of American soldiers by apportioning little bits of their souls into their organs and transplanting said body parts into the unwitting Americans.
My players had a wonderful time with it, with the exception of one: the power gamer in our party who is constantly looking for ways to make his character bigger/better/stronger and generally ore able than the others, even if it means trafficking with supernatural horrors and sacrificing a few of his friends to get what he wants. For example, when I ran the original Divine Fire scenario, his character wanted to sell the others out to the ghoul in order to learn more about the mythos, a plan that he never carried out because he missed a session and I was a bit too new to running CoC to feel comfortable adding that complication to the plot. This may be all well and good in the World of Darkness, but in CoC, engaging the Mythos creatures with that kind of reckless abandon is a fast route to insanity and an untimely death, a fact I've warned him of several times. It could also be the reason why he's not so keen on being a part of my CoC adventures, and why he misses so many sessions.
Anyhow, the Power Player had missed the session where the characters found the operating theater full of advanced surgical equipment that the team's doctor was unable to identify, and the strange room full of organs in jars, and he decided not to pay very close attention to my recap at the beginning of the next session. When the party finally unearthed the disembodied brains of the Nazi officers, floating in jars attached to crude robotic bodies, he failed his San check and slipped into a temporary insanity. I rolled Echolalia on the Temporary Insanity chart, and told him that his character was horrified beyond the capacity for speech, and could only helplessly repeat what those around him were saying.
The rest of the party entered the room, and those who remained sane enough to do so made contact with the brains. When one of the party members asked what they had done to themselves, one of the Nazi brains told them, "The fungus has made us what we are! Gods among men!" Now, I had been dropping hints that the aliens who gave the Nazis the advanced surgical instruments weren't exactly animal in nature, describing the places where the Mi-Go had been as being coated in a thin film of unidentifiable fungoid sludge. The Power Gamer, upon hearing the Nazi's statement, decided that he would drop the echolalia and manifest his insanity by scraping the mold off the walls and shoveling it into his mouth. He continued to do this through the rest of the scenario, every time I asked him what his character was doing. Later, when I asked him what he was hoping to accomplish, he told me that he ate the sludge because he heard the brain say that the fungus had transformed the Nazis into gods, and he was hoping that if he ate enough of it, he, too would be granted the same powers. When I asked him why in the hell he thought eating handfuls of mold would transform him into a brain in a jar on top of a robot body, he simply shrugged and told me that it made sense to him at the time.
After that incident, the Power Player politely bowed out of the CoC chronicle, and I began the next session by announcing the sad news that his character had died following a bizarre illness brought on from consuming unhealthy amounts of the unknown ooze. As you can imagine, none of the other players were very upset to see him go.