This achievement requires you to have an answer that gets 100% of the votes in all three rounds of a bracket.
You can do this one of two ways, depending on what browser you're using:
Use the Multifox add-on for the Firefox browser. Install it and each new tab opened (ctrl+T) can be assigned a different profile by clicking the fox icon in the browser in the top right corner.
Click on the person image in the very top right of your browser. Go all the way down to "manage people" and click on it, then click on "add person" in the bottom right corner. Once you click it, click an image for them then click "save" in the bottom right corner. This will open a new pop up window for that person.
I'd suggest using the Firefox method as it's easier to navigate tabs than windows, but I couldn't get it to work for some reason so I wen't with Chrome.
Regardless of what method you use, open five tabs/windows and join an "Enough About You" Fibbage 3 game. Once the game starts, each person will have to answer a question about themselves. Write down an answer you'll know is the right answer (like the letter A or something), then when it pops up, have everyone choose that answer and you'll get your achievement.