During the Genosha level you will arrive at a tower to get to Sinister. At the bottom is the Wheel of Insanity you have to spin to progress, and it will land on Magnetic Apocalypse. Shoot all the balloons around this wheel.
You will then have to jump up the metal plates to get to the next level of the tower, and the next wheel. Spin it, and it will land on Cow. Shoot this cow as it flys by, and the rest of the balloons at this wheel. Trophy will pop after.