For thirty years, Johnson had arrived at work at 9 A.M. on the dot.  He had never missed a day and was never late.

Consequently, when on one particular day 9 A.M.  passed without Johnson's arrival, it caused a sensation.  All work ceased and the boss himself, looking at his watch and muttering, came out into the corridor.

Finally, precisely at ten, Johnson showed up, clothes dusty and torn, his face scratched and bruised, his glasses bent.  He limped painfully to the time clock, punched in, and aware that all eyes were upon him said,

"I tripped and rolled down two flights of stairs in the subway.  I nearly killed myself."

His boss replied skeptically, "And to roll down two flights of stairs took you a whole hour?"