Coca-Cola, Ke-kou-ke-la
The name Coca-Cola in China was first rendered as Ke-kou-ke-la.  Unfortunately, the Coke company did not discover until after thousands of  signs had been printed that the phrase means "bite the wax tadpole" or  "female horse stuffed with wax" depending on the dialect. Coke then  researched 40,000 Chinese characters and found a close phonetic equivalent, "ko-kou-ko-le," which can be loosely translated as "happiness in the mouth."

Pizza Hut P'Zone
Pizza Hut is advertising their new dish, a calzone they named the P'Zone. It is pronounced like "pezón", the Spanish word for "nipple". Susana says the Pizza Hut PR dept. in Texas told her they knew about this before launching the campaign.

Hong Kong Tourist Board
According to TravelBiz.com in April, 2003 the Hong Kong Tourist Board tried to either pull their ads or have their slogan changed. But it was too late to change the campaign that was on billboards throughout Hong Kong and in British versions of Cosmopolitan and Conde Nast Traveller.
The slogan that was running "Hong Kong: It will take your breath away." unfortunately coincided with the SARS epidemic that resulted in numerous deaths. Shortness of breath is one of the main symptoms of SARS.

International Wine Glass Symbol
Stevadores in an unnamed African port, seeing the international --but evidently not universal!-- symbol for 'fragile' (a wine glass with snapped stem) presumed it meant that some idiot had sent a cargo of broken glass.  So they obligingly pitched all the cases overboard into the harbour!

Hyundai Pony
Richard Seamon reports: Hyundai had problems with the Hyundai Pony. In Cockney rhyming slang, "Pony" is short for "pony and trap", meaning crap.  It didn't deter Hyundai, they still marketed it in the UK (circa 1982).

Perdue Chicken
Chicken-man Frank Perdue's slogan, "It takes a tough man to make a tender chicken," got terribly mangled in another Spanish translation. A photo of Perdue with one of his birds appeared on billboards all over Mexico with a caption that explained "It takes a hard man to make a chicken aroused."

Electrolux Vacuum
The Scandinavian vacuum manufacturer Electrolux tried to sell its goods in America but didn't help itself with this slogan, "Nothing sucks like an Electrolux."

Coors
Coors put its slogan, "Turn it loose" into Spanish, where it was read as "Suffer from diarrhea".

American or Braniff Airlines
When American Airlines wanted to advertise its new leather first class seats in the Mexican market, it translated its "Fly In Leather" campaign literally, which meant "Fly Naked" ("vuela en cuero") in Spanish!

Pepsi
In Taiwan, the translation of the Pepsi slogan "Come alive with the Pepsi Generation" came out as "Pepsi will bring your ancestors back from the dead."

Reed Business News
A few years back Reed Business News relaunched itself with the branding: "If it's news to you, it's news to us.".
It was replaced after a couple of days...

Signs
From a Japanese information booklet about using a hotel air conditioner:
Cooles and Heates; if you want just condition of warm in your room, please control yourself."
From a brochure of a car rental firm in Tokyo:
"When passengers of foot heave in sight, tootle the horn. Trumpet him melodiously at first, but if he still obstacles your passage, then tootle him with vigor."
Two signs from a Majorcan shop entrance:
- English well talking.
- Here speeching American.
Sign in a Bombay hotel (where water is still routinely fetched from the Ganges potentially giving you diarrhea or worse):
All water has been personally passed by the management.