Since the triumphal reception of the ukulele in the US from 1915, this has been a widespread mnemonic for the most common tuning of the ukulele in GCEA (C6):

This mnemonic has even entered the memory-psychological literature:

In tuning the ukulele, this catch phrase can be sung:
„My dog has fleas —“¹⁾

A somewhat unique mnemonic device is the one to remember the pitches for tuning a ukulele: D, G, B and E.²⁾ The notes are sung but invariably with the curious words: My Dog Has Fleas.³⁾

The exact origin of this mnemonic is unknown. In itself, the words do not match the names of the strings. However, I suspect that this is the parody of a well-known 19th century English hymn, Nearer, My God, to Thee. It was already reported at the end of the 19th Jhs. that church-scorn scoffers in the US parodied this song to „Nero, my dog has fleas“.⁴⁾ This parody was very popular among students in the following years; this was the group that came in contact with the ukulele most intensively.

The first verse of Nearer, My God, to Thee begins:

The second measure is CFAG, which is almost identical to GCEA when you put the reentrant G to the end and trade F for the E removed by a semitone step. So it was probably originally sung and played as CEA (up the scale) and then G (down the scale).

Probable original notation

Since the word ukulele is probably derived from 'uku „flea“ and lele „jumping“, the association with fleas-stricken dogs is easily explained. In any case, there are already numerous allusions to the connection between dogs and ukuleles in the press in the 1920s.

So I was persuaded that I could get a banjo and play it as I did the ukelele. I could use the same tuning which by the way is quite simple. A ukelele properly tuned emits noises, when the strings are struck slowly, like someone saying, „My dog has fleas.“ You can't miss it.

Donald Jones in The Franklin Evening Star 18.10.1938, p. 2

Millie sat in a chair nearby practicing with a ukelele and singing: „My dog has fleas — fleas — fleas,“ but always the word fleas was off key. (…) „My dog has fleas — fleas — This is the way to tune up a ukelele, you know. My dog has fleas. There, I've got it!“
And Millie began to play …

Lucy Huffaker in: The Rolla Herald 9.2.1939, p. 6

Niagara Falls, N.Y., May 18 (AP) — A music store owner told this story.
A small boy walked into his shop and said:
„I want to buy a flea string for my ukulele.“
When the proprietor suggested he meant a „D“ string, the boy replied:
„No, I don't. When my teacher tunes my ukulele, he sings 'My-dog-has-fleas' and it's the flea string that broke.“

The Gettysburg Times 18.5.1939, p. 1

On July 17, 1939, George Cruesling and Claude Malani filed their copyright to the following song:

"Say My Dog Has Fleas When You Tune an Ukulele"

Written in a comic vein, „My Dog Has Fleas“ will be the David Rose⁵⁾ original musical piece on the „Holiday for Music“ program, Wednesday, at 10:30 p.m., EST, over CBS. Fantasy woven on the four notes that ukelele players warble as they tune up, „My dog has fleas“ is another of the rhythmic novelties for which the young composer-conductor is noted.

The Circleville Herald 2.7.1946, p. 11

Some time ago Rose took an old ukulele effect known widely as „My Dog Has Fleas“ when that tiny stringed instrument was a staple on porches and beaches, and arranged the four notes into a complete composition. The notes are simply the tune plucked out by the four ukulele strings without fingering. Rose orchestrated them first in a pizzicato effect, then as a soft and sweeping passage using a large violin choir and brasses, proceeding to other quasi-concert results which are excellent musically and amusing in their sharp evasion of stuffy tradition.

Jack O'Brian, in: The Morning Herald (Union Town, Pennsylvania) 31.8.1946, p. 4

Victor Young (1900–1956) and his orchestra recorded a recording of „My Dog Has Fleas“. It actually starts with the leitmotif GCEA.⁶⁾

Of course, after the Second World War, the origin of this custom – the song parody – seems to have been forgotten, so that it was only related to the ukulele itself.

In the episode The Ukulele of The Phil Harris-Alice Fay show, which aired on 30.10.1949 on the radio, Phil Harris presents himself as a ukulele player. A friend visits him and tries to Harris' ukulele My dog has fleas to intone. Harris comments on the weird singing:

Your voice is kind of lousy, too.

Internet Archive

What does „My Dog Has Fleas“ mean to you? It's the sentence used in tuning a ukelele. And about ukes, 9 times as many are being manufactured now as before World War II.

Amarillo Daily News 28.3.1950, p. 5

As another English mnemonic, Good Children Eat Apples is common.

In Japan, the female personal name Hanako-san 花子さん is used as mnemonic. Allegedly, the comedian Maki Shinji called this while tuning his ukulele and made it popular.

(Illustration: Ukulele Lesson)

I recommend Gib Carl einen Apfel as a German mnemonic.