This gate (the rectum) is known as Nirrti, or the painful gate

Expressions researched:
"This gate is known as Nirrti, or the painful gate"

SB Canto 4

When one is called by nature to evacuate, one also experiences pain. The friend of the living entity who accompanies him through this gate is named Lubdhaka, which means "greed." Due to our greed, we eat unnecessarily, and such gluttony causes pain at the time of evacuation. The conclusion is that the living entity feels well if he evacuates properly. This gate is known as Nirṛti, or the painful gate.

SB 4.25.53, Translation and Purport:

Another gate on the western side was known as Nirṛti. Purañjana used to go through this gate to the place known as Vaiśasa, accompanied by his friend Lubdhaka.

This is a reference to the rectum. The rectum is supposed to be situated on the western side of the eyes, nose and ears. This gate is especially meant for death. When an ordinary living entity abandons his present body, he passes through the rectum. It is therefore painful. When one is called by nature to evacuate, one also experiences pain. The friend of the living entity who accompanies him through this gate is named Lubdhaka, which means "greed." Due to our greed, we eat unnecessarily, and such gluttony causes pain at the time of evacuation. The conclusion is that the living entity feels well if he evacuates properly. This gate is known as Nirṛti, or the painful gate.