Vitamin J Share definition Flag Slang term for male semen. Generally used by females to describe the events that transpired a previous evening. I can't get enough of his vitamin J! A high protein milkshake consisting of vitamin J. Vitamin J by Pierre August 17, 2006 Words you can keep railfan mug chonk mug chud mug based mug 67 mug slime mug mogging mug chopped mug thot mug glazing mug huzz mug yams mug larp mug unc mug cracked mug simp mug baddie mug bop mug lolcow mug