Definition:
"Fanboy" is a slang term used to describe a person who is an extremely enthusiastic fan of something or someone, to the point where they may be seen as biased or irrational in their support.
Use case:
You might use the term "fanboy" to describe someone who is overly devoted to a particular brand, product, celebrity, or hobby. For example, a fanboy of a particular video game console might defend it vehemently against any criticism, even if it's objectively not as good as a competitor. The term can be used in a derogatory way to suggest that the person is not thinking rationally, but it can also be used in a more lighthearted way to acknowledge someone's passion for something.
• The new Star Wars movie was a hit with fanboys, but left casual viewers feeling indifferent.
• My little brother is such a fanboy of Minecraft, he won't play any other game.
• The heated debates between fanboys of rival gaming consoles often escalate into full-blown arguments.
• The comic book store was filled with fanboys eagerly waiting for the latest issue of their favorite series.
• I may not be a fanboy of any particular band, but I do love listening to music.
• Despite the criticism, the fanboy remained steadfast in his unwavering devotion to the superhero franchise.