The American military is trying to capture an island which is occupied by a single Italian soldier (perhaps in the South pacfic??). Wave after wave of US military power is hurled against the island, suffering 100% casualties. No one survives. Still, the lone Italian soldier remains in place. Finally, a massive attack by the Marines is thrown on to the beaches. From this attack, only 1 American survives to make it back to HQ. The Commander asks "What went wrong?" and the wounded marine says "There are two Italians on the the island!"
It's a dumb joke. But I just love the fact that this joke was (obviously) intended to tell the opposite story -- one American is a match for the entire Italian army. But it got twisted around, and was told to me as a joke about weak Americans. And I was so young, I just thought it was funny, even though I didn't really understand it.
When I got older, I learned about Ancient Rome, and the Renaissance. Not too many countries can measure up to the Italian achievements. For Kerry to make "an Italian joke" says a lot about his maturity.
If people took history seriously, they would be amazed at the similarities between the Roman Republic and American government.