Last season, bare butts were the new nipples. And prior to that, it was all about, well, nipples. This spring, cleavage is back and with a vengeance. Designers showed necklines to the navel with skin bared everywhere. From Vena Cava to Altuzarra to Badgley Mischka to ... oh, this list is endless. Are the looks practical? Of course not! But they're titillating! (Sorry, our inner 13-year-old boy just came out.) Refinery29 wonders if it's too much skin. "While the lithe sprites on the runway paint a more romantic picture of this provocative plunge trend, we ask you: On the street or the red carpet, is this look super stylish or just totally trashy?" Showing the goods is nothing new; hell, it was the cornerstone to Tom Ford's womenswear career. And celebs are already busting (har har) out, as we all saw at the Emmys. We're not planning on wearing these looks on the street, but we just might start doing some push-ups all the same. And for the love of all that is right, remember the cardinal rule of deep necklines: Tape is a girl's best friend.