"Do be do be do" is a phrase associated with the American singer and entertainer Frank Sinatra. It gained attention because of the way he sang it in his version of the song "Strangers in the Night," released in 1966.
In the song's scat section, Sinatra sings the phrase "doobie doobie doo" with a rhythmic and playful delivery, which has a jazzy and improvisational feel to it. It became a distinctive and memorable part of the song and is often associated with Sinatra's unique style of vocal performance.
It's important to note that "do be do be do" doesn't have a specific meaning or any deep significance. It's more of a vocally expressive element used for musical effect and entertainment value in the context of the song.