Written and first recorded (as “Get the Mop”) by Henry “Red” Allen (1944).
Hit versions by Johnnie Lee Wills & His Boys (US #9/C&W #2 1949), Doc Sausage & His Mad Lads (R&B #4 1950), The Ames Brothers (US #1 1950).
From the wiki: “‘Rag Mop’ is a 12-bar blues, adapted by Tulsa Western Swing bandleader Johnnie Lee Wills (Bob Wills’ younger brother) and steel guitarist Deacon Anderson from an earlier song, ‘Get the Mop’, composed by Jazz trumpeter and band leader Henry ‘Red’ Allen. (Wills and Anderson would later be successfully sued for plagiarism by Allen’s publisher.)
“Considered a novelty song, the lyrics to ‘Rag Mop’ consisted almost entirely of spelling out the song title; because of that, it is sometimes referred to as ‘Ragg Mopp’. Wills and his band first covered ‘Rag Mop’ for Bullet Records in 1949, but the most popular version of the song was recorded by The Ames Brothers and released by Coral Records in 1950. Doc Sausage & His Mad Lads also covered the song in 1950, peaking on the R&B chart at #4.