This is the most luck-based achievement in the game. It requires that you roll a double six with one player two times in a row. The key to getting this achievement with as little frustration as possible is to double tap when rolling. When you quickly (but precisely) double tap the dice to roll them on the board, they will frequently not even flip and land in the same exact position as the previous roll. Use this to your advantage. Play a four-player game to 2 million dollars and keep rolling normally until you get double sixes. Then use the double tap trick to attempt to get the double sixes a second time and unlock the achievement. It is best to practice the double tap trick on random dice rolls to try to perfect it for when you finally roll the double sixes. It doesnt seem to be 100% guaranteed to work, but the skill can be honed a bit.