"Sucking up to" is a slang phrase that usually refers to a person who is trying to gain favor or advantage through flattery or subservience. However, there are several other words and phrases that can be used instead. These include ass-kissing, brown-nosing, pandering, ingratiating, groveling, fawning, toadying, bootlicking, and kowtowing. Each of these words implies a similar sense of insincere flattery or excessive deference, and may be used in different contexts or with different degrees of formality. Whether in the workplace, politics, or social situations, it's important to communicate with integrity and honesty, avoiding the pitfalls of sucking up and insincerity.