I have a bunch of plastic ballerinas at work.
Only two are pictured, but I have perhaps twenty - the contents of a standard pack.
They live in a cabinet above the chair in my cubicle.
I have a lot of crap in this cabinet: blank DVDs, a toothbrush, toothpaste, books, packets of personal photographs, my headphones. Almost every day, I need to reach in and take something out.
Often, when I reach for, say, my toothbrush, I will disturb the ballerinas and one or two will fall onto my desk. Sometimes I will return them and close the cabinet. Other times, I leave them lay where Jesus flang them.
As you can see, five are currently down. Over time, all twenty will have fallen. When all are out, I will replace them in the cabinet, and the cycle will begin anew.