Boring in this case means something like "unmemorable" or "indiscernible". The great big dice roll that happens for everyone at the start of the big game has way too many variables to land on the same values twice, so being boring is a choice to hide the diff between you and the person you're talking to. ("Audit what you've hidden" is a neat way to phrase that.)

If you rolled all 1s for charisma, that would be unboring, it'd be memorable!