Brinny Boy Share definition Flag Brinny Boy is this screeching noise taht you hear from the ground. he usually gets ran over by MTBS and iliana and aysha usually cook him and feed him to george! #coolkid O.M.G, Brinny Boy just got squished by this MTB😵 💫 Brinny Boy by slimelicker57 March 6, 2022 Get the Brinny Boy mug.