I swear, I have never been accused of having these.
Ok, maybe I have.
To be fair, I think that everyone who has reached a certain amount of Japanese proficiency (when you learn how to say こんにちは, for example) has to deal with people over-complimenting their ability. Most of the time, even students of Japanese language are aware of themselves enough to understand when they really are the "bomb-diggity," and when people are just being polite. Sometimes, however, you come across that rare person who just doesn't get it and thinks that he/she is God's gift to the study of Japanese. I'd say that those people are suffering from delusions of grandeur.
Of course, that's not the only source of delusions of grandeur in the world, so feel free to come up with your own examples.
Delusions of grandeur
Just 'cause you were a big deal out in the boonies, don't go getting any delusions of grandeur. Things here are on a different level.