Bad Milo! (2013)

A man named Duncan lives with his wife, Sarah, who worries about his constant stress. One day, he schedules an appointment with a gastroenterologist after experiencing a rather serious level of gastric stress the night before. During the appointment, the doctor and nurse spot a large "polyp" in his intestinal tract. After seeing a large amount of stress at a very fast pace from work with his boss placing him in charge of firing employees, where a man his age is in a relationship with his mother, and his wife is making him see a very eccentric therapist who keeps asking about his father issues, something unusual happens. The polyp forms into a 2-foot-tall sentient being, and begins killing each person the creature sees as a source of stress with each day. The local news reports the murders as having been attacks by a rabid raccoon.

Duncan's therapist informs him that the creature is the living manifestation of his life's stress built up over time, and that mythology of this type of being states that the best way to eliminate it is to bond with it so it doesn't act so irrationally. In an effort to bond with it, Duncan names this strange anal-dwelling creature Milo.

First, Milo kills his co-worker, then the E.D. doctor he didn't need, yet who wouldn't stop calling him. Soon enough, Milo kills Duncan's boss in an elevator during an investigation by the FBI at his office building. When it finally attacks his father, who apparently had a being of the same species, and begins killing the other being, Duncan loses his grip and moves Milo and himself to a hotel room far away and safer for potential victims. This doesn't work, much as it seems to at the outset and Milo tracks Sarah down to her house party where a violent battle ensues between Duncan and Milo. Ultimately Duncan dismembers Milo's left arm and legs, and finally saves its life, vowing to never ignore Milo's important influence and make amends with Milo, successfully doing so before Sarah reinserts Milo back up his anus.

Ultimately Milo's bloodline is discovered to be carried on through Duncan's unborn son, the embryo of the new creature being seen in the system of the unborn fetus.