A kind of joke that starts with something like "Okay, so these two black guys walk into a bar, and the bartender..."
A Mexican, a black, and a white guy are in a bar having a drink when a good-looking girl comes up to them and says "whoever can say liver and cheese in a sentence can have me". So the white guy says "I love liver and cheese." she says "that's not good enough." The black says "I hate liver and cheese", and she says "that's not creative", and then the Mexican says "liver alone cheese mine."
- that's what you call a racist joke.
to go for a vincent actually means go take a piss.
the phrase comes from a Quentin Tarantino film PULP FICTION, in which the character named Vincent Vega (starring John Travolta), is always "oh so desperate" to use the bathroom facilities all the time.
Vincent: ...so not only i shot that guy in the face, i have a very bad luck walking out of the toilets... never consider to go for a Vincent, unless you expect something catastrophic to happen later...