It is entirely possible for a person to be arrested for criminal harassment for allegedly "flipping the bird" to a third person. However, there are numerous published cases at the state and federal levels holding that "flipping the bird" in and of itself is an expression of one's Constitutional Right under the freedom of speech.I suspect that the neighbor is getting a friend who is in law enforcement to "mess" with your son and yourself where there is most likely not going to be any charges filed concerning the incident that you have written about. However, to be on the safe side, I suggest that you consult with a criminal defense attorney about the matter you have written about.