It's hard to think clearly, however, when you're one of today's third-wave feminists, particularly when you've been lugging a 50-pound mattress around your college campus for the past eight months as a public "performance art" project/protest accusing your former friend of rape. This, alas, is the burden of Emma Sulkowicz, the infamous Columbia University "Mattress Girl," who graduated on Tuesday from the Ivy League school with her signature mattress in tow. Several friends joined her on stage, preening — one even offered up an awkward facsimile of a Queen Elizabeth wave — as the not-so-humble, symbolic mattress was greeted with enthusiastic applause.