Green’s Dictionary of Slang

a nothing, a trifle.

1692		J. Hacket Memorial of John Williams Pt 11 131: When all the Stuff in the Letters are scann’d, what Fadoodles are brought to light?
1923		J. Manchon Le Slang.
2001		Theatre in City Pages XXII:1098 19 Dec. 🌐 [They] apparently didn’t think it was necessary to concoct much of a story to connect the songs. They have, instead, tossed off some fadoodle about a girl on a Greek island inviting three of her mother’s former lovers to her wedding, believing one of them to be her father.