Consider, for instance, the bit of dialect spelling printed in a Missouri newspaper in 1900, “Boyz vill be boyz.” Using vill for will is apparently intended to approximate the accented English of a German speaker. But boyz in that context does not represent a different pronunciation—instead, it just looks different. (In fact, German-inflected English would be more likely to change the pronunciation the other way, with the /z/ sound shifting to /s/ through what linguists call “final devoicing.”)

Spelling reformers have long sought to apply logic to English orthography, to bring it more into line with the phonetics of speech. In 1906, when the crusade for spelling reform was at its peak (with such luminaries as Theodore Roosevelt and Andrew Carnegie backing the effort), one newspaper advertisement for an Oregon clothier poked fun at the effort by writing the ad copy in “the Phonetic way,” changing “men’s and boy’s suits” to “menz and boyz suts.”

This kind of playful spelling took on new significance within the 1960s counterculture, especially in the music scene. Following the path of The Beatles, who changed a letter from beetles, many new bands tweaked the spelling of preexisting words, and that included changing the plural ending -s to -z. Thus, in 1966, a noisy band in New York City called themselves The Godz. Pittsburgh had The Jaggerz, and an Ohio band dubbed themselves The Boyz. (A hard-rock band in Los Angeles would also take the name The Boyz in the 1970s.) Meanwhile, some bands went further with unusual respellings, as when the British band Slade released their 1973 hit, “Cum on Feel the Noize” (later covered by Quiet Riot).

In the 1980s, R&B and funk acts (most famously Prince) used distinctive spelling for album and song titles. The “boyz” tradition was continued by an L.A.-based funk group called Skool Boyz. In the world of rap music, one of the biggest acts of the time was Heavy D & The Boyz, which put out its first release in 1987. After that, in the late ’80s and early ’90s, numerous other “boyz” emerged in hip-hop and R&B, most notably Philadelphia’s Boyz II Men (who took their name from the 1988 New Edition song “Boys to Men”).

While Singleton’s use of the letter z in Boyz n the Hood partook in this musical legacy, the same kind of respelling has emerged in other arenas of playful usage. Advertisers have used it for slogans—such as “Beanz Meanz Heinz,” a British tagline used by Heinz Baked Beans since the 1960s—or for product names, like the Trollz and Bratz dolls. As Leslie Savan observed in her book Slam Dunks and No-Brainers, since the ’90s, the z has been used to communicate a youthful edge, “to look hip-hop fresh,” though such appropriation has often flopped, such as when the Fox Family Channel launched the short-lived Boyz Channel and Girlz Channel in 1999.

Meanwhile, on the internet, the z-for-s substitution has been a hallmark of ironic leetspeak, as seen in such intentional misspellings as n00bz (for newbs, short for newbies”) or lulz (a variant of lols for laughs). While the -z ending may now seem rather played out, appropriate only for self-conscious parody, it’s worth remembering the summer of ’91, when Boyz n the Hood represented a jolt to the system, one administered by a young film director seeking to upset the norms, spelling included.