Languages

A linguistics professor was lecturing his class one day.
'In English', he said, 'A double negative forms a positive. In some languages, though, such as Russian, a double negative is still a negative. However, there is no language wherein a double positive can form a negative.'
A loud voice from the back of the room piped up, 'Yeah, right.'

A clever pilot, with the help of his passengers, managed to thwart a hijacking attempt. He realised when talking to the hijacker that he didn’t speak French, despite trying to force the plane to land in France. So, he told the passengers over the intercom that he was going to do a rough landing to throw the hijacker off balance and that the passengers should be ready to pounce. He even moved the women and children to the back of the plane.

Let's end it with a few of solid mis-translations:
Here speeching American.-sign in a Moroccan shop.
No smoothen the lion.-sign in a zoo in the Czech Republic.
Specialist in women and other diseases.-doctor's office in Rome
Fur coats made for ladies from their own skin.-window of a Swedish furrier
Our wines leave you nothing to hope for.-on the menu of a Swiss restaurant
If you consider our help impolite, you should see the manager.-sign in an Athens hotel.
Teeth extracted by latest methodists.-sign in Hong Kong dentist's office.