jiz bib Share definition Flag Referred to as a homosexuals beard. The purpose of the beard, aka jiz bib, is to protect the man from ejaculate spilling on to his shirt during oral sex. Good thing rainman had a large jiz bib, or matt would have ruined his new shirt. jiz bib by VousCrew October 28, 2008 0 0 Get merch Get the jiz bib mug. Buy Now — $32.95 See more merch