sciencehabit writes: Physicists have shown that everyday mug sizes produce natural frequencies that just happen to match those of a person's leg movements during walking. This means that walking alone, without any other interference, is tuned to drive coffee to oscillate in a mug. But the researchers also found that even small irregularities in a person's walking are important: These amplify the wilder oscillations, or sloshing, which bumps up the chance of a spillage.
Never appeal to a man's "better nature." He may not have one.
Invoking his self-interest gives you more leverage.
-- Lazarus Long