the residue that forms around your nostril shortly after snorting illegal substances.ie; methamphetamine, cocaine, etc.

A casual invitation / threat used by an individual that is not afraid of fucking someone up.

white, sometimes crusty remnants of post-nasal drip caused by "doing a line" or "some lines" of an illegal substance such as cocaine or methaphetamine (speed). Possession of any of these illegal drugs is classified as a felony. These remnants will often form ring(s) in the opening of the nasal passages.
Felony Ring(s)

A circle of powder, ringing the inside of one's nostril which can be left over (or I suppose even BUILD UP) from the ingestion of an illegal drug in powder form by "snorting", or quickly inhaling said powder through a small straw or glass tube (usually known as a "Tooter")inserted directly into a nostril. Most common among cocaine users; however, the term "felony ring" was first coined by meth-amphetamine users, since if the wrong person noticed, it could lead to a felony charge, as the laws are quite strict and harsh for what could be considered MINISCULE amounts of the drug. In essence, a felony ring contains enough of the drug, in weight, for one to be charged with a felony.