The Pain Hole is one of the Manotaurs' rituals that must be taken in order to become a "man."
The hole is seen in "Dipper vs. Manliness," when Dipper asks the Manotaurs to give him pointers on becoming a man. After agreeing to help him, Chutzpar tells him his first task is to plunge a fist into the Pain Hole. Testosteraur then taunts the Pain Hole and plunges his fist in. A moment later, he mysteriously starts to scream, sweat in pain and run away. After seeing this, Dipper is hesitant about putting his fist in the hole, but when the other Manotaurs cheer him on, he puts his hand in, but instantly screams, causing nearby several birds fly away.
The Pain Hole looks like an ordinary hole in the ground, with a sign saying "Pain Hole" next to it. Around the edges there is dirt. It is unknown what actually causes the pain but there appear to be pieces of jagged rock protruding from inside the hole.
- 106. "Dipper vs. Manliness"