In the winter of 1928, Joe Kennedy decided to stop to have his shoes shined before he started his day's work at the office. When the boy finished, he offered Kennedy a stock tip: "Buy Hindenburg." Kennedy soon sold off his stocks, thinking: "You know it's time to sell when shoeshine boys give you stock tips. This bull market is over." A timely move considering that the stock market would soon resemble the fate of the airship Hindenburg itself.