A shadiddle is where you take the classic car games padiddle and shiner and combine them into one fabulous sexual act. So, when a girl is giving a guy head he cums in her eye and then proceeds to say padiddle, on account of her having one eye "out". After that, when she is holding her eye he pees on her and on account of the yellow color punches her and says shiner! Then after these two actions are completed it is a successful shadiddle.
by Shandawgg May 14, 2009