Bay seniors concerned that twerking may throw their hips out, might want to consider learning a more flirty and erotic form of dancing. What could be more passionately adult than the Argentine Tango where you and your partner are glued together? Slow, sinuous and steamy there are classes for it all over the Bay Area. Check them out on Google. Out on Taraval in the City the Pick School of Ballroom Dancing starts a beginner’s class this Friday at 7. It appears that the first class is free and the rest $40 each.