A Gleenis is a word originating from South Jersey, usually used as a synonym for roof tiles, particularly pool/swim club roof tiles. Gleenises can also be used to describe any type of tile, including floor tiles.
Joe: Whatcha doin'? Huh? Huh? Huh?
Matt: Dude, stop being so annoying! Go count the gleenises or something...
Joe: I already have! There are 32,038 gleenises at the pool!