Run-A-Muk Share definition Flag The physical act of letting oneself go. Can often be witnessed by young beautiful people spending time at Grandma's. I can't wait to go Run-A-Muk at Grandmas on Sunday morning Run-A-Muk by BigBadBrownyBrown September 8, 2011 0 0 Get merch Get the Run-A-Muk mug. Buy Now — $32.95 See more merch