Half-Sac Share definition Flag A descriptive name for a male with only one testicle in the bag of skin hanging below his penis (the scrotum). Boy: “Hey dad, why do you call Cousin Mike ‘half-sac’?” Dad: “Because he’s only got one nut son!” Half-Sac by JJtheJackass June 11, 2019 0 0 Get merch Get the Half-Sac mug. Buy Now — $32.95 See more merch