When you stay over at a bros house for the night and sleep in a shed or tent, but need a wank because of a long day, so you separate the shed or tent with a thin piece of cloth or sleeping bag and nut in your own sleeping bag. Shed + tentie = Shentie nut

A mix between latin words(praeseNTI) meaning (present) and (SHEath) meaning (vagina) also meaning body in Chinese, Shenti is slang for a very attractive female with an extremely dirty vagina and or ass hole.