The word itself is "פֿאַרשפּאַר" (far-shpar). It's pronounced roughly as:
* far (like "far" in "far away")
* shpar (like "spar" in "sparrow" but with a slight emphasis on the "sh")
However, please be aware that using this word can be considered offensive and inappropriate in most situations. It's best to avoid using it unless you are in a very specific and comfortable context.