Where did it come from? I don't know. It's not original to me. But our friend, Lou Goncey, liked it & that reminded me to share it with you!
Ability Score Generation: In tabletop adventure games in general and fantasy games in particular, generating ability scores is a lot of fun. In order to determine your ability scores, use the following method.
Draw a tic-tac-toe board. Across the top, label the columns “Str”, “Dex”, and “Con” for Strength, Dexterity and Constitution. Label the rows “Int”, “Wis”, and “Cha” for Intelligence, Wisdom and Charisma.
Throw three six-sided dice and add the pips, and write that number in the top-left box. Repeat this process eight more times for the other eight boxes.
For any given number, it may be assigned to the ability of the row it’s in or column it’s in, but not both. When you use a particular number, cross it out afterwards. You will find that three scores are left over. Use one for your starting gold - remember to multiply it by ten - and discard the other two numbers.
This method generates above-average ability scores, but the moderate incidence of low scores means these characters resemble regular folks, only a little better. These kinds of characters are quite viable but also within the normal range for Men.