This rhythm pattern seems very famous and is oftenly used to knock on someone's door, sometimes as a code:
Does it have an history? Where does it come from?
This pattern comes from a fanfare often used at the end of a musical performance called "Shave and a Haircut- Two Bits"
I found this reference to it on Wikipedia: 
In music, the call "Shave and a Haircut" and the associated response "two bits" is a simple, 7-note musical couplet, riff or fanfare popularly used at the end of a musical performance, usually for comic effect. It is used both melodically and rhythmically, for example as a door knock.
"Two bits" is an archaism in the United States for 25 cents, a quarter. "Six bits" is occasionally used. The final words may also be "get lost", "drop dead" (in Australia), or some other facetious expression. In England, it was often said as "five bob" (slang for five shillings in pre-decimal coinage), although words are now rarely used to accompany the rhythm or the tune.
answered Mar 1 '17 at 12:30
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Hi! Thank you, Sir! I still wonder how did you find this question, and the answer, but nice find! – Bebs Mar 1 '17 at 13:53
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1Well, as for the question I subscribe to the music group inside of the top of the list. The answer? Just one of those things that was lodged in my head LOL I don't remember where I first saw it – Scott ResistTHIS Hamilton Mar 1 '17 at 15:30
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I 'knew' the answer even though our restrictive work network didn't show the image ! This was used in great effect in the film 'Who framed Roger Rabbit' to tempt the pesky rabbit from his hiding place in the speakeasy. – Pat Dobson Mar 3 '17 at 8:01
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"Shave and a haircut - two bits" is well known in the US, at least for those of us older than 50 or 60. – jrw32982 supports Monica Oct 10 '19 at 18:10
In the Netherlands a comical music group, called The Cocktail Trio, had a hit in 1965 with a song about a flea circus. Ultimately a flea makes the biggest jump ever to the moon. The song ends with the "Shave and a haircut... two bits" riff with the Dutch line "Die zien we nooit meer... terug" wich translates as "We'll never see him... again". Everybody in the Netherlands knows this text to the riff, even if they don't know the original song.
The music to the song was composed by Ad van der Gein and Hans Ninaber. The Cocktail Trio also recorded an instrumental version with the international title Tiddley Winks. I don't think the notes of "Shave and a haircut" were invented by them. To me it sounds like something more traditional.
