Story-related achievement, unlocked through natural story progression by siding with Kyle and attacking Cartman at the end of your second trip through the school. Unlock both KKK Hero and Elven Hero on a single playthrough by making a save at the end of the level right before choosing whether to attack Cartman or Kyle. After defeating one, re-load your save, and choose and defeat the other. There is no long-term effect of your choice, it's just a matter of which character speaks a few lines of dialogue. The lines are even exactly the same, so the order doesn't matter. When you re-load your save, it should start you outside of the classroom again, and anything you did immediately before entering the class, like friending Lemmiwinks or checking the cabinets and lockers and both classrooms and the hallway, will be undone. Make sure to redo those actions if you plan to continue on with the game after you reload the second time.