Never underestimate the power of female flatulence.This weekend, Universal’s smutty femme-driven laffer “Bridesmaids” hit the B.O. sweet spot, crossing $100 million in domestic grosses. And while “Bridesmaids” is the 10th pic to reach that figure this year (“Kung Fu Panda 2″ also crossed $100 million this weekend), the U laffer’s road to success wasn’t always obvious. First, there was the question of whether male audiences would join femmes to see a raunchy comedy revolving around female main characters. Despite a successful South by Southwest premiere, pre-opening buzz was muted. Finally, Warner Bros.’ fellow R-rated behemoth, “The Hangover Part II,” bowed just two weeks after “Bridesmaids.” But since debuting on May 13, the film has held up admirably in theaters — it hasn’t dropped more than 27%, in fact — with weekend perfs consistently ranking it in the top five, boosted by male turnout. Even last weekend, when “Bridesmaids” went head-to-head with “Hangover II,” the U laffer dropped just 21% with the weekend’s best hold overall. “Bridesmaids” has three weeks before the next R-rated comedy, Sony’s “Bad Teacher,” bows Stateside. The pic also has yet to start its overseas run, though American comedies can be a tough sell with international auds. Up first is Australia — a popular starting point for U.S. comedies — on June 16, followed by Russia and the U.K. the weekend of June 24.