Some folks I know were playing this a couple years ago. One of them opened with "Can your person fit three tennis balls in their ass?" When answered in the affirmative, he correctly guessed the person.
The first question I usually ask is "Does your person have facial hair or a vagina?"
At first glance it might seem racist for them to have every character but one be white, but I suspect the makers of Guess Who did this precisely because they didn't want race to be a part of the game, and didn't want kids playing it by skin color.