The achievement so called: "Punching Bag" - Unlocked when the player lets the gangsters beat up Johnny.
This can be obtained in Act 1. When you get the movie reel to the cinema. You will eventually get to a spot where there is a movie screen. Head down the stairs towards the screen, after Didi talks to her dad, the bad gangsters show up and eventually start beating up her dad. Didi tells you to put in the movie reel to stop the fighting, DON'T, and watch them beat up poor Johnny for about a minute or so and the achievement is yours. Enjoy