Two Americans were out drinking and found themselves at the bus stop after a night on the town. While they were standing there, a convertible drove up.
The driver shouted out, "Parlez vous français?"
The drinking buddies looked at each other, shrugged, and looked blankly back at the driver.
"Sprechen Sie deutsch?" the driver tried.
Again, the two shrugged and said nothing.
"¿Habla usted español?" shouted the driver.
The two looked at each other and shrugged as the motorist sped angrily away.
"Do you think," said the one, "maybe we should try to learn a foreign language?"
"Nah," said his friend. "That guy there spoke three, and it didn't help him a bit."
a night on the town = staying out in the evening to celebrate (with alcohol)
convertible = car with no roof
shrug = to raise the shoulders to show you don't know the answer
What's So Funny?
The two Americans spoke only English, so they couldn't understand the visitor's questions in his three languages. From their view, it's not useful to know those other languages because Americans--at least these two guys--don't speak them.