y/n

y/n could mean:

The abbreviation to "Your name", usually used in fanfics in such. Sometimes the reader, sometimes a self-insert OC.

Or, in slang terms,

The abbreviation of, "Young Nigga", usually referring to a person.

(Term 1), Hello Y/N! How are you doing today?

(Y/N is usually replaced with a name, whether it's yours or an OC's.)

(Term 2), Yo, wassup my y/n? How ya' doin?