People who live nearby or in your general neighborhood. In additional to the obvious geographical meaning, the term has deep emotional, philosophical and (some say) sexual implications.
Person 1: Yo - you wanna invite the neigh-neighs over tonight?
Person 2: Yeah! Let's invite them for yokie-dokes!
A common phrase used when one feels a feeling of strong bewilderment. While "What the Hay Neigh" originated from equestrian roots, it is now used far and wife outside of the field, a phrase known to all.
Person 1: I despise horses! They are some of the worstcreatures known to man.