The story
Uncertain; perhaps from scadoodles (“unspecified large amount, number, or quantity”) (US, slang) (although the Oxford English Dictionary notes this is attested slightly later), or from boodle (“whole collection or lot”) (US, dialectal), caboodle (“large collection of people or things”) (US, slang) + -s (suffix forming pluralia tantum).
Etymology from Wiktionary, CC BY-SA 4.0.