Boot-lickers are those people who excessively flatter and grovel for personal gain. However, there are several synonymous terms that can be used to describe their behavior. Sycophants are people who flatter and act obsequiously towards someone important to gain advantage. Flatterers are those who use excessive and insincere praise to win favor with others. Toadies are individuals who fawn over superiors, often to the point of becoming subservient. Brown-nosers are those who ingratiatingly flatter or curry favor. Ass-kissers and brown-nosers are both crude terms that describe the act of trying to gain favor through excessive flattery. Ultimately, all these synonyms describe behavior that is insincere and self-serving.