BeyonJay Share definition Flag An STD, characterized by an all-over rash that swells up like Jay Z's lips. Also the name of Beyonce and Jay Z's child. Dude, Lydia totally caught the BeyonJay from Kyle last night, it's gross. BeyonJay by Jayceee25 September 5, 2011 0 0 Get merch Get the BeyonJay mug. Buy Now — $32.95 See more merch