As far as I know, many drug addicts grow a nail on their little finger, so that it is more convenient for them to take a dose from small bags and "sniff" it directly from the nail by immersing it in the nostril.
to the above I will add that it was also possible to print letters with this nail. in extreme cases picking your nose.
symbols symbols symbols symbols
There is also a version that this is a prison tradition, emphasizing the special status of a person who does not work. In work, the nail would break. If it is long, it is proof of "thieves' purity".
I "wore" this for a long time. For the sake of self-control - I was nervous and often wanted to hit someone. And here - you clench your fist and feel - the nail painfully digs into the skin.
Slowly it became a kind of "prohibition ritual" - when I realized that I was losing my temper or something was going wrong - I clenched my fist tightly and it seemed to become easier - I realized that I was hurting myself and others by one hands. I became calmer. But it took a lot of time.
In addition, it was a useful thing in the household - it helped to work as a hookah man, in origami and pepakura, to twist hand-rolled cigarettes, and a lot of places.
Roads to build them, by the way, inconvenient - a lot is hammered under the nail itself, which is both wasteful and simply pale =)
This is a Masonic tradition, a kind of sign of "our" (along with others). It is known, for example, that Pushkin wore a copper thimble on his little finger, covering his nail. Later in the mass consciousness it became associated with aristocracy in general. Well, cocaine addicts in the early 20th century also contributed.
Whether this feature has deep roots, I do not know. But in the circles of radio amateurs and microelectronics specialists of the 80-90s, the nail played the role of an additional tool. He helped a lot during small jobs. Always at hand and never lost.