Bithsauce Share definition Flag 1. Achieving high or extreme levels of "bith" or P.M.S. 2. Being a bitch but not actually being called a bitch. Your mom is a bithsauce to the ultimate max. Bithsauce by Bithicus April 21, 2004 0 0 Get merch Get the Bithsauce mug. Buy Now — $32.95 See more merch