“Eight to the bar” is a 30s and 40s phrase used on uptempo dance tunes, as a command to the rhythm section to emphasize 8 beats to every bar of music, making it feel like double-time (as opposed to 4 beats to a bar).
Calling for eight to the bar meant something like, “Speed up the music. Let’s dance!” though what was actually said was, “Let’s boogie!”
Boogie-woogie (later swing) tunes counted eight-to-the-bar were, from the outset, dance music. The point of eight-to-the-bar was to be a fast dancer’s count, for jitterbug, Lindy hop, and swing style dances. So, the call to “beat it eight-to-the-bar” was a request from dancers to play up tempo, with strong rhythm, suitable for dancing. In the space that you might count a typical measure (‘a-one, two, three, four’), the Boogie Woogie player would play 8 bass notes.
“Beat Me Daddy, Eight to the Bar” is a song written in 1940 by Don Raye, Hughie Prince, and Ray McKinley. It follows the American boogie-woogie tradition of syncopated piano music. The song was first recorded in 1940 by the Will Bradley orchestra. The recording was re-issued by Columbia Records on its Hall of Fame series featuring landmark songs.
The title adopts 1940s’ hipster slang coined by Raye’s friend, Ray McKinley, a drummer and lead singer in the Jimmy Dorsey band in the 1930s. McKinley kicked off certain uptempo songs by asking pianist Freddie Slack (nicknamed “Daddy”) to give him a boogie beat, or “eight to the bar.” The nickname “Daddy Slack” was also used in the 1941 recording by “Pig Foot Pete” with Don Raye singing in Slack’s band.
It’s easy to understand how a non-musician could find the expression confusing. “Beat me” is, of course, a pun, and the expression means “Give me eight beats to the bar,” the bar representing a musical measure marked by a strong beat and some number of secondary beats.
I missed the music of the 30s and 40s but in the 50s and 60s I loved to “jive.” I’m not a musician but I suspect jiving was just as fast as boogie-woogie.