Joey is a down-and-out college student always looking for some fast cash and his roommates, Kevin and Brian, happen to always have nice things just lying around.
Last moth, after Kevin bought a new mountain bike for $2,000, Joey happens to notice that the same exact bike is for sale in the classified for $1,950.
So, Joey takes Kevin's mountain bike to the resale shop and receives $2,000.
Then he turns around and buys the same bike for $1,950 from the ad.
Joey's just netted $50 and no one is the wiser.
Yesterday, Brian just bought a brand new video game console for $900, but the local electronics store has the same console listed at $750.
So, Joey takes Brian's console to the resale shop and receives $900.
He then buys the same game console for $750 at the electronics store.
Joey's again come out on top by gaining $150 on someone else's goods.
Joey makes his money by selling high and buying low.
To read how short selling works in the trading environment read here.