Monsters Inc. I'm Your Boo Girls Tanks Mary, or Boo, is so cute even monsters can't help but love her! Join in the fun with the Monsters Inc. I'm Your Boo Heather Black Racerback Tank Top! The lovable Boo is portrayed in her monster suit beside the phrase "I'm Your Boo" in white text down the front of this black Monsters Inc. tank top. 50% Polyester, 25% Cotton, 25% Rayon. Designed with raw-edge hems.