Frosted Sandpaper

I cut up little strips of sand paper and keep a handful of them in a baggie with a piece of cloth. Then when I have a clay piece that needs smoothing, I'll take the baggie and the clay with me in the car to make good use of my "car-time" (we often have long rides to work). Sometimes I'll sit in the living room with my baggie and clay and sand/buff as I otherwise relax, but I never sand/buff in the kitchen which does double duty as my craft "studio". Now, my other half occasionally puts an empty glass in the freezer so he can have a nice frosty chilled "mug" o' beer. Sometimes it's in there for days before he remembers to use it. Yesterday he pulled out the glass - which had been chilling since the weekend - and found a used strip of sandpaper frozen to the inside bottom of the glass.

I wouldn't have believed it if I hadn't have been there when he pulled it out.
How on earth did that happen?!? One of life's little mysteries I guess.