noun phrase. Sand in the butt-gina is never restaurant-quality.
Real citation: "sandy butt crack syndrome is a very common and dangerous event which if not treated immediatly can lead to 'itchy ass crack for 3 days disease' and 'omg, i just farted and a plume of sand came out my anus'"
(May 15, 2005, Livejournal, http://community.livejournal.com/saucy_ian/757.html)
Made-up citation: "There are many hazards of being a summer camp counselor: toxic lake swims, sandy butt crack syndrome, poo in the pool, felonious co-counselors, and a terrifying fiend of the forest called The Mope. There are even reports of a 'Pope' that supposedly exists somewhere off camp grounds, but I hope that is all hearsay."