Over-friendliness is a term that describes behavior that is excessively friendly and overly familiar. There are several synonyms for this term that can convey similar meanings but with slight variations in nuance. One possible synonym is "smarmy," which implies insincerity and an intention to flatter or manipulate. Another synonym is "gushy," which suggests overly effusive and exaggerated expressions of affection. "Obsequious" is another choice, indicating a willingness to excessively cater to someone's needs or desires. Other synonyms for over-friendliness include "unctuous," "fawning," "sycophantic," and "oily." These words can be used interchangeably in context, depending on the tone and connotation desired.