It is, I suspect, a long-term effort of selective muscle control learned over a period of time. Such control is indicative of the tenets of the art of bellydancing, if my research is to be believed. Humans are often inclined to be somewhat exhibitionist with their achievements, and tend towards the sensational to highlight them. It is an extremely curious attribute, but it is no doubt entertaining - and, if the reaction from the male and the flirtatious behavior indicated by the female is to be believed, intended to be what one might consider 'enchantingly erotic.'
Is a cold shower indeed an effective method to quench such desires?