Hofstadter
"This is the reference implementation of the self-referential joke."
"This is the reference implementation of the self-referential joke."
Douglas Hofstadter is an American author who has written several books about philosophy, mathematics, and science. He is perhaps most famous for his book Gödel, Escher, Bach which explores "strange loops," or self-referential systems. "Meta-" is a Greek prefix meaning "outside" or "beyond." As an adjective, "meta" informally refers to anything self-referential, like the last phrase of this sentence. An example of the use of such a term can be found in 1313: Regex Golf.
At first reading, the six word autobiography in the second panel, "I'm So Meta, Even This Acronym", may seem unfinished, however the clue is in the final word. An acronym is an abbreviation formed by the initial letters of a series of words, and reading the first letter of each of the six words in order yields "ISMETA", completing the sentence and setting up the self-reference where it reads "I'm so meta, even this acronym IS META". Hofstadter himself did something similar in Gödel, Escher, Bach in the chapter "Contracrostipunctus", where the first letter of each line spells out the phrase "Hofstadter's Contracrostipunctus Acrostically Backwards Spells J.S.Bach" - and taking the first letters of each word in that sentence backwards does indeed spell "J.S. BACH".
This comic is probably a reference to Six-Word Memoirs, a project launched in 2006 in which people "tell their life story in just six-words". This comic may additionally be a reference to the meme "explain <whatever> in six words", which was making the rounds at the time.
In the title text, a reference implementation is, broadly, an example of how to implement some feature during the software development process. In this case the feature is a self-referential joke, and the sentence itself is, correctly, self-referential.
Hofstadter has been referenced before, in the title text of 555: Two Mirrors and 608: Form. Furthermore, his famous book has been directly spoofed in the title of 24: Godel, Escher, Kurt Halsey. Finally, the self-reference reference ("IS META") is also a typical concept used most famously in 688: Self-Description but also in several other comics.