An Upper East Side man has been arrested after going on a racial tirade against a black postal worker in the neighborhood.

Police say that the incident occurred around 9 a.m. on March 18th. Suspect Joseph Cullen, 33, approached the 58-year-old male victim, who was on line with a coworker at a food cart on 3rd Avenue and E. 55th Street buying breakfast.

It's unclear what prompted the incident, but Cullen allegedly started spewing profanities and "anti-black statements" at the mailman; the News reports he called him a "black hood rat," "black piece of s---" and the N-word. Cops add that Cullen spit in the man's face, and then fled on foot.

Police add that the two men did not know each other beforehand. Cullen was arrested this past Thursday, and has now been charged with racially motivated aggravated harassment.