According to The Oregonian, a shaved vertical slash in the eyebrow indicates gang participation. It is occasionally called “carved.”
In some instances, particularly in schools, pupils with “carved” eyebrows are instructed to fill them in with a pencil. Some schools do not require this of their kids unless instructed by law enforcement officials.
Keeping price tags and size stickers on hats may be compared to shaving a line in the eyebrow. This can also be seen as evidence of gang membership.
A shaved line in the eyebrow, according to a source for The Oregonian, is intended to impress rather than intimidate.