Reading comprehension

What does the word ' end-of-the-tongue' mean? It comes from this sentence which I have been reading - a novel ' A tree grows in Brooklyn' written by Betty Smith. It reads : Mama gave Francie instructions about going out to buy something for lunch. " Take eight cents from the cracked cup and get a quarter loaf of Jew rye bread and see that it's fresh. Then take a nickel, go to Sauerwein's and ask for the end-of-the-tongue for a nickel."

"But you have to have a pull with him to get it"

" Tell him that your mother said," insisted Katie firmly.