When Madonna sang “Strike a pose!” in “Vogue,” we don’t think Downward Dog was the position she had in mind. But by now, it’s fair to say that the famously flexible Material Matriarch has helped popularize yoga for plenty of other pop princesses and their fans: most recently, we’ve panted with animal lust over Shakira’s beautifully bendy choreography in her new “She Wolf” video. So it makes perfect sense that Back Bay Yoga (364 Boylston Street, 2nd Floor, Boston, 617.375.9642) would host Pop Divas Unite! A Yoga Celebration tonight, a two-hour class set to the upbeat music of our favorite pop icons. Want to enjoy a Shavasana set to Cher? Take a bind while listening to Britney? Sit in Lotus to Lady Gaga? That’s exactly what you’ll do from 7:30 to 9:30 p.m. The $20 class accepts reservations in advance here (and we strongly recommend them). And boys, don’t cry: we’re promised at least one noteworthy divo will be added to the mix. Now, does anyone know the Sanskrit word for “Moonwalk”?