sycophant
A person who flatters powerful people to gain favor.
A sycophant is someone who praises and flatters powerful people in an insincere way, hoping to gain favor or advantage.
Imagine a student who constantly tells the teacher how brilliant every lesson is, laughs extra hard at the teacher's jokes, and volunteers to help only when the principal is watching. That's sycophantic behavior: the praise isn't genuine, it's calculated to win special treatment.
You can spot a sycophant because their flattery feels hollow and overdone. They might shower the class president with compliments while ignoring everyone else, or suddenly become very friendly with whoever gets chosen as team captain. A sycophant agrees with everything a powerful person says, even switching positions to match whatever the boss or leader currently thinks.
Real respect means being honest and willing to disagree respectfully. Friends tell you the truth, even when it's uncomfortable. Sycophants tell you only what they think you want to hear. That's why being called a sycophant is an insult: it suggests you lack the courage to be genuine and the integrity to speak your mind.