N + 쟁이 colloquially describes a person who is known for, or frequently exhibits a certain trait or characteristic. It can be negative or positive. Here are some examples:
거짓말쟁이 - a serial liar
멋쟁이 - a stylish person
고집쟁이 - a stubborn person
욕심쟁이 - a greedy person
엄살쟁이 - someone who fakes/exaggerates
말쌍쟁이 - a troublemaker
개구쟁이 - a brat
아부쟁이 - a sycophant, suck up
겁쟁이 - a coward
공부쟁이 - someone who's always studying
고자질쟁이 - a snitch
수다쟁이 - a chatterbox