Pull apart the buttocks of your consenting sex partner, and as per the French greeting kiss each inner cheek from left to right whilst dragging your nose across their bumhole. Voila the dirty bonjour.
"Oh la la" exclaimed Angelique, as I bent her over and warmly welcomed her with a dirty bonjour.
In a billingual province such as Quebec, you have to greet people in English and in French when you work in customer service. After a while, it just becomes one word because you're so used to repeating it over and over. As well, it MUST be "bonjour" that is said first, because French (on the whole) are unforgivably uppity. And don't even THINK about just saying "hi!"