One sixth of a pound more than 3 ounces?

My local Braums' (it's a famous Oklahoma dairy farm with many food
outlets) has a menu item labeled "Sixth lb hamburger...".

At first I thought that should be "Six-pound...", hyphen and all, but
then I realized that would mean a rather large hamburger.

Then I got it: If they'd written "3-oz hamburger..", who would buy it?

And, while on the same topic, here's what Bank of America wrote to me:

"You could qualify to apply for up to $25,000 to pay off credit card

Talk about ambiguities!