Another favorite of mine is the Iron Man 2008 Movie Muscle Chest Adult Costume. It includes a red and gold muscle torso top and a character mask. The costume is available in adult size 42-46. You can just pair it with your black pants and you are ready to rock the night away.
If you want the whole ensemble, you can check out the Iron Man Muscle Adult Costume. The red and yellow outfit includes a plastic 2-piece mask (front and back pieces that Velcro together) and bodysuit with muscle torso and legs. The costume is available in one size and will fit up to adult size 46.