"FHB" was actually code for "Family Hold Back." Our friend's mother was discreetly letting everyone in the family know to let the guests help themselves to special dishes but to only take a little for themselves.
Our friend said this usually happened when there wasn't quite enough of a certain dish to go around, but her mom didn't want guests feeling like they couldn't dig in. We're sure there were times when our friend saw a favorite dish disappearing onto someone else's plate and sorely wished she could break the rules!
This sounds like a really practical and reasonable family rule, and a gentle way to teach children to let guests go first. Do you or did you have any secret family codes like this in your house?