"Hold your thumbs." I first heard this from my brother-in-law, when he was visiting my parents place for the first time with his daughters. My mom wanted to show the kids something, and his girls of course, wanted to see as well. He shouted this at them as they ran off, and afterwards I asked him what he meant by it. 

He demonstrated by holding his thumbs in his fist, and explained that you can't pick up and break something if you were holding your thumbs. I thought it was genius, and it stuck with me. That was when I decided he was a good dude, and approved of him dating my sister. They've been married for ages now, turns out he WAS  good egg.

Anyways, I've never heard anyone ELSE say it, but when I was planning this scene, it made perfect sense. Maybe it's a common phrase used by Akyn parents? Well, it sure is now! Thanks brother!