There are numerous synonyms for the term "sucks up" that people use in various situations. One of the most common is "brown nose," which refers to someone who flatters others to gain advantage or approval. Another synonym is "kiss-up," which also implies that someone is trying to ingratiate themselves for personal gain. The term "bootlicker" is also used, and it has much the same connotation as "brown-noser." Other synonyms for "sucks up" include "ass-kisser," "toady," "yes-man," and "smooch." No matter the term used, all of these synonyms carry the same negative implication that someone is ingratiating themselves for personal gain.