McThrobinsin Share definition Flag a very large penis, it is extremely thick and has many veins. the common color is white. it has enough gurth to crush a semi. Wow! that guy last night, he had a McThrobinsin McThrobinsin by ThePenisMaster July 11, 2009 0 0 Get merch Get the McThrobinsin mug. Buy Now — $32.95 See more merch