A girl with a mouth full of sand gives a guy a blow job, and his shaft is scrapped uncomfortably by each individual grain. Needless to say, the experience isn't enjoyable for either party, and the couple is hopefully wasted on a beach - otherwise why the fuck would her mouth be all sandy.
Kate got drunk and sand blasted some dude on the beach.
The act of wrapping sandpaper around the penis (rough side out of course) before engaging in anal intercourse with someone who REALLY needs put in their place. Only to be performed when lube-free anal just isn't quite enough punishment for the dirty receiver.
"That bitch is supposed to be my girlfriend, but I caught her fucking three of my friends!"
"Give her a Sand Blaster...that oughta teach her a lesson"