We had really weird "nicknames" for certain foods growing up and I still don't know how some of them started. A baguette was "cutty bread," cheesy pasta was "taggy cheese" (would have made some sense if we used tagliatelle, we didn't) veggie burgers were "huxleys" and Hobnob biscuits were... "flugelhorns" (why?)
Re: What is some sayings your family use that would really confuse outsiders/