These pants could get you banned from class.

Among marathoners in the know, American-made "Sofie Run Tights" from LA-based company Splits59 are a very big deal. How big? At $108 per pair, they're constantly selling out. Fans say they've run 50 miles in them with zero chafing. We slipped on a pair, and our legs instantly felt cool. We love the hidden slit for an iPod cord, the mesh detailing, and most of all, the smooth, sleek line they give our rear. But when we were bending beside the mirror, we gasped. These pants are NSFY.

That is, Not Safe For Yoga. In the upright position--power walking, hiking, running--they're the best. But in Downward-Facing Dog, the reason they're called "tights" shines through (and so does our underwear). They seriously show off our assets.

We aren't brave enough to wear these booty-lovin' bottoms to a class (at least, not without a long top), but they're our first pick for jogging.

Guess they're too cool for school.

Sofie Run Tights go so fast that they're always running out--but you can find them locally at many of these retailers (call ahead to check for stock). To get on the list for the next edition of Run Tights, called "Aria," email here.

Know someone who's always on the run? Send her this email.