An experience at the drink machine

My co-worker stood there in front of the drink machine with a determined expression.  The fluid yet mechanical way she grasped the upside-down foam cup from its tower of duplicates and lifted, inverting and cutting its calculated path in the air, showed a patience in practice reminiscent of Olympic balance beams and console-game tournaments.

Her first selection, Dr. Pepper, had been the reigning office favorite for years.  The nozzle had been replaced four times, by her six years' reckoning.  The others, never.  A light touch on its button with a perfectly vertical finger--her trademark--activated a foamy, splattering double-click.  The stream had stopped almost as soon as it started.

She swished the tablespoon of soda in the cup twice and flipped the cup over the drain grate in a motion so surprising that I cannot remember the mechanics of it.  How did her wrist turn?  How much of it emptied out?  I couldn't remember seeing it, but I do remember what happened next.

She placed the cup right-side up on the grate, applying her vertical finger again, this time to the Diet Dr. Pepper button.  Its red light glowed for the seven seconds it took to fill her Styrofoam tumbler, as the dark caramel-colored liquid confectionery whirlpool swirled, then ceased, then fizzed, then stilled.

She had pretended not to notice me, but now turned with perfect cognizance to look me square in the eye and explain, glee suppressed by a serious face, "I mix a very dry Dr. Pepper."