dagwood, n. — Green’s Dictionary of Slang

dagwood n.

[the favoured food of the character Dagwood Bumstead in Chic Young’s syndicated cartoon strip Blondie, launched in the US in 1930]

(Aus./US) an extra-large sandwich.

1948		Ladies’ Home Journal Sept. n.p.: Giant three-inch Dagwood sandwiches [HDAS].
1960, 1975		Wentworth & Flexner DAS.
1982		N. Keesing Lily on the Dustbin 121: His anticipated elaborate meal on bread known as a ‘Dagwood’ or ‘Bumstead Special’ to Australians.
1983		N. Heard House of Slammers 23: He spread a thin layer of mayonnaise over each slice [...] and built a Dagwood sandwich of modest proportions.
1983		R. Price Breaks 393: Petty was scarfing down a Dagwood.