Green’s Dictionary of Slang

punk n.3

[ety. unknown]

[late 19C+] (US) bread; thus yellow punk, bread and butter.

In compounds

punk and gut (n.)

[1920s–60s] (US tramp) a bread and bologna/cheese sausage sandwich.

punk and plaster (n.)

[late 19C–1930s] (US) bread and butter.