Have the group sit in a circle, each dad seated beside his child. The lead player starting the game says, "My father owns a grocery store and sells something beginning with the letter "C" (or any other letter). The lead player will be thinking of a grocery store item which begins with the stated letter (such as cereal or crackers in this example). Each player is allowed three guesses in turn. If the right answer is not guessed at all, the player starts all over again with a new word. The person who guesses the correct answer has the next turn as leader.
This game can be varied by using other kinds of stores (clothing, music, sporting goods, etc.).