A small amount of ones food given to a friend. When a Nib is asked for, one cannot decline the Nib otherwise the Nib rule is broken. It is frowned upon to decline a Nib, and can result in a punishment.
A Black Sabbath song. Contrary to common belief, "N.I.B." doesn't stand for "Nativity In Black," in fact, it doesn't stand for anything. Drummer Bill Ward had a beard that singer Ozzy Osbourne said looked like a pen nib. The band named the song after the nib and added initials so the name would be more mysterious. There are two Black Sabbath tribute albums named Nativity in Black, based on the faux acronym.