We English folk are pictured with bad teeth.
A Snooker set has a black ball, a pink ball, green, brown and yellow balls, a selection of red ball... and the white ball.
By comparing one's teeth to a snooker set, one implies that ones teeth are in a horrific state. By adding in that one only needs a white one for one's personal snooker set, one imlies once again that one has bad teeth - that is, one has no white teeth.
Does one get what the other one is saying?
Sorry, a teensy bit happy - passed the 5000 posts mark.