This is a true story from the japanese embassy in US .

A few days ago Prime Minister Mori was given some Basic conversation traning

  before he visits Washington and meets president Barack Obama.................

The instructor told Mori Minister when you shake hand with president Obama

please say ' how are you ' then Mr. Obama should say i am fine and you ?

now you should me too afterwards we translators will do the work for you it 

looks quite simple but the truth is

 when Mori met Obama, he mistakenly said 'who are you?' (instead of how are you)

Mr Obama was a bit shocked but still managed to react with humor :

'well, I am Michelle's husband , ha-ha

then Mori replied ' me too , ha-ha.

then there was a long silence in meeting room