I've tuppenced before in my early years. But what the heck does "bib" mean. I couldn't find it.
Anyway, you get an A++++ for your post!
When you go to dinner, you're supposed to put on your finest "bib" so the tucker doesn't stain your shirt. Your best bib and tucker.
This only applies to the more refined eating establishments. Down at "The Trough and Brew" they don't much care.