There is a scene with two couples engaging in sexual activity during a ritual. The two women undress showing full nudity (shaven lhabia visible) , a mans buttocks are briefly seen. This is quickly interrupted by the Psycho Killer.

A man takes a knife and cuts a long deep gash into his hand and blood oozes out. Brief but pretty graphic.

A man gets bludgeoned to death by a sledgehammer to the head. We see initial impact then a quick cut away, then we see the aftermath. Highly graphic. Afterwords the killer sticks his hand into the wound to use the victims blood.

Language is very infrequent and hardly any until the last 30 minutes and includes only 4 uses of "fuck". And a couple once or twice uses of other profanities.

Some casual drinking, and a scene where several people ingest tabs of LSD.

The killers look, behavior, and psychology are all highly disturbing and menacing.

The psycho killer likes to hide, jump out and violently attack people.