5/8ths Share definition Flag The smallest dick was 5/8ths of an inch. This is said to make fun of a guy for having a small penis or to tell him that he has no chance with girls. 5/8ths! 5/8ths by ohlifex August 13, 2010 0 0 Get merch Get the 5/8ths mug. Buy Now — $32.95 See more merch