Verb
let one go (third-person singular simple present lets one go, present participle letting one go, simple past and past participle let one go)
(slang, idiomatic) To fart.
I'm not going out of my way looking for devils; but I wouldn't step out of my path to let one go by. Robert E. Howard
Superstitious, they did not go after her. They had a robber-god which they worshipped in a cave. His creed declared: ‘For every fifty travelers robbed and slain, let one go free. The gods care for excess in nothing.' Tanith Lee