In the days when Usenet newsgroups (NGs, now called "Internet discussion groups") were more popular (see: soc.motss), one signed one's postings using a four-line piece of text called a".sig file". The .sig file took its name from the name of the file where it was stored. Because the name of the file began with a period, it was partially hidden in the file listing.
Your .sig file typically had your name, email, perhaps your mailing address and maybe your telephone number. The more creative people managed to integrate some ASCII art or a favorite quotation into their four lines of plain text. In the soc.motss NG, a group of self-identified "bears" (gay men who are big-bodied and hirsute) began to put in cryptic lines of letters and numbers in their .sig files. This was NBCS, the Natural Bear Classification System, and it was first codified in November 1989 as a way for bears to recognize each other, even outside of the safe haven of soc.motss. The NBCS, commonly known as "bearcode", provided a suprisingly detailed indication of what its owner looked like, was into, etc. It was kind of like an online version of the hanky code, only it gave much more information.
Around the time I started hanging out in soc.motss (early 1990s), I became part of the SmurfGangTM, where I was given the smurfname Smurf-at-Large. A group of primarily non-bear motssers, they developed the SmurfCODE as an adjunct of bearcode. Whereas bearcode's primary characteristic was "fur" (how hirsute you were), SmurfCODE emphasized "laugh" (what kind of sense of humour you had). SmurfCODE was designed specifically to be orthogonally compatible with bearcode so one could have combine both codes into one. I have no bearcode, but my smurfcode is S5/8 b++g+ly+zn++o+xa++uv-j++k4. (Read the spec to decode it!)
In 1991, SmurfCODE 1.04 was codified. TwinkCode v1.12 was released two years later for people who didn't feel that either NBCS or SmurfCODE spoke to them. This was now a parody of a parody of a tongue-in-cheek representation of a largely outmoded social signifier system. It was getting silly. Nevertheless, some of us dutifully went through and figured out what our various codes were. I even had my smurfcode and twinkcodes printed up on (blue, naturally!) return-address labels.