Neishy Share definition Flag Neishy is a term used to descrive a male with a large undercarriage or 'shlong' Person 1: Damn he has a huge weapon Person 2: It must be Neishy. Neishy by James McNeish April 7, 2008 0 0 Get merch Get the Neishy mug. Buy Now — $32.95 See more merch