This troper was particularly horrified at the one where a man jumps into a wood chipper that sprays his bloody remains all over his ex's house (and into her face, as she was leaning out of the window).
The man who wakes up and discovers he's just a head and a spinal column.
The most disgusting part may be a throwaway line about how you know the victim's dying "when it turns red, then eventually black." Doubly so if you know what causes Black Blood in real life.
Most of it, really. The series, with few exceptions, is deliberately intended to make the viewer incredibly uncomfortable if not terrified. Unsurprising given that the opening more or less tells you it's about people who have totally broken down beyond all rationality.
The cultists in the mall. Particularly Lord Awesomo. This is what happens when psychotic hipsters form an equally psychotic cult. When tossing a cult member into the deadly jam, instantly killing him, all Awesomo has to say is "He died ironically. You older generation just don't get our sense of humor."
Imagine watching your best friend since childhood slowly lose his grip on sanity until he's actively killing people.