mash up Share definition Flag Irish word talking about a way to cook some spuds by breaking them down. Adopted by Jamaicans to describe breaking up other people's tings. If he dont bring my weed im gonna mash up im bloodclaat yard mash up by hairy mo April 18, 2004 0 0 Get merch Get the mash up mug. Buy Now — $32.95 See more merch