The act of finding a Chinesehooker, impressing her with lies of you being a cage fighter in Beijing, then taking her up the ass with sweet and sour sauce and make her talk in Cantonese or Mandarin.
Dude, that hooker though I was a cagefighter back in '94. She was so impressed, she let me do the Dirty Chinaman...for free...
If someone says they're going to have a dirty chinese, it means they're looking forward to what is expected to be an immensely delicious chinese take-away.
An Irish saying, it involves the popular misuse of the word 'dirty' as slang for something beyond the realm of every other positive word in the English language.
It is not used in a racist manner.
Lookin forward to a great big dirty chinese tonight