Note: In the context of E621, and to eliminate confusion this tag should only be used where the affected character has a penis and has an Erection. "Death_Arousal" should be used in the case of characters without a penis."

"Death Erection" is the penis equivalent to the "Death Arousal" tag.

Also known as "Angel Lust", "Rigor Erectus", or "Terminal Erection", this phenomenon is a post-mortem erection, technically a priapism that can affect those of all sexes.
They can be observed in the corpses those who have been killed in a manner by which the central nervous system experiences trauma, such as by hanging, shooting, or other means by which pressure on the cerebellum or spinal cord occurs.

This phenomenon received the moniker "angel lust" because the genitalia of the affected becomes engorged in the same manner by which arousal occurs.
For those with a Penis, a discharge of assorted seminal fluids such as prostatic fluid or mucous may occur. This involuntary discharge resembles pre-ejaculate or ejaculation, further contributing to the "angel lust" moniker.
For those with a Vagina, a discharge of blood from the vagina may occur.
In all sexes, a discharge of urine may occur.

Arousal may begin prior to the death in question, which can ensure this phenomenon occurs post-mortem, and is often depicted in snuff artwork.

https://en.wikipedia.org/wiki/Death_erection