siiyupp Share definition Flag The Dirtbike riders way of saying goodbye. "man im out to hit my mates ramps and supercross track...Siiyupp!." "sounds good... have a good one....over and out siiyupp". siiyupp by mezza39 August 13, 2007 0 0 Get merch Get the siiyupp mug. Buy Now — $32.95 See more merch
