The crunchy, flake-like concoction of snot and blood that feels about the size and texture of a football made out of broken glass when it's lodged in the back of your nose. Notable for the relief you feel when finally firing off a farmer hanky and defiling the local area with the raisin and related, viscous detritus. Initially appears as a raisin, but looks more and more like one as you roll it up, let it dry on your finger, or stick it on some scratch paper for continued observation.
Dave's allergies and constant nose picking gave him a constant stream of nose raisins. His sister was always grossed out finding them stuck and drying to her computer keyboard, looking like dried cranberries, with dark flecks of her brother's familiar snot.