"I saw this in a movie about a bus that had to speed around the city, keeping its speed over fifty, and if its speed dropped, it would explode! I think it was called 'The Bus That Couldn't Slow Down'."
If you haven't seen the 1994 action blockbuster starring Keanu Reeves and Sandra Bullock, you don't need much more than Homer Simpson's famous bit to understand the plot. A domestic terrorist rigs a bomb on a Los Angeles bus to activate once the bus hits fifty miles an hour. If the speeds drops below fifty, the bus explodes. If any passengers leave, the bus explodes. What do you do Keanu? WHAT DO YOU DO?