"Keep A-Knockin' (but You Can't Come In)" is a popular song that has been recorded by a variety of musicians over the years. The lyrics concern a lover at the door who won't be admitted—in some versions because someone else is already there, but in most others because the knocking lover has behaved badly.

Early versions are sometimes credited to Perry Bradford and J. Mayo Williams. Variations were recorded by James "Boodle It" Wiggins in 1928, Lil Johnson in 1935, Milton Brown in 1936 and Louis Jordan in 1939. A similar lyrical theme appears in "Open the Door, Richard" from 1946, but from the viewpoint of the one knocking.

In 1957, when Little Richard recorded it as an uptempo rock and roll song "Keep A-Knockin'" reached number two on the U.S. R&B charts and number eight on the U.S. pop charts. His version is usually credited to Penniman (Richard's legal name), Williams, and Mays. Little Richard played the song on an episode of Full House. He recorded a version of the song with different lyrics as an introduction for the NBC show Friday Night Videos. The song was also featured in the theatrical trailer for Home Alone. The song was used in the film Christine when Dennis is trying to break into the car, but is then scared off by the song that suddenly starts playing from the car radio.

Rolling Stone magazine later ranked "Keep A-Knockin'" at number 442 in its list of the "500 Greatest Songs of All Time". An answer song titled "I Hear You Knocking", written by Dave Bartholomew and Pearl King, was recorded by Smiley Lewis in 1955. The drum part on Little Richard's song, played by Charles Connor, also inspired later songs. Eddie Cochran's "Somethin' Else" features an identical drum beat, played by Earl Palmer. The drum introduction on the Little Richard recording was used by John Bonham for introduction to the Led Zeppelin song "Rock and Roll".

...
Wikipedia