Two box fighters hunt across Sylt for Eva...

Hmmm.

Zwei Boxkämpfer jagen Eva quer durch Sylt.

x, q and y are very rare letters in German. Luckily, there is the name of an island in the North Sea, Sylt. And a word we took from English: boxen, which means to box, and Kämpfer means fighter, so the Boxkämpfer is a boxer (boxing fighter). That also takes care of one Umlaut which is important in creating German-looking text. Quer means across. There are too many l/c e, a and r to make this as efficient as the quick brown fox, but it is a fun sentence and easy to remember. If you're German.
We have many more that are impossible to translate and difficult to remember, even for us.

So roughly it means:
Two boxers hunt across the Island of Sylt for Eva?
Who originally started using the phrase?

Is it wrong for me to like STRANGLE strangle? Originally I just used RSTLNE like on Wheel of Fortune, but I wanted to see an A and a G. Then I wanted a word to arrange them in for my memory.

(You could use "strängle" if you needed an Umlaut, but then that would be silly.)