I own any form of humor shows fear and inferiority. Irony is simply a kind of guardedness. So is a twinkle. It keeps the reader from criticism. Whittier, when he shows any style at all, is probably a greater person than Longfellow as he is lifted priestlike above consideration of the scornful. Belief is better than anything else, and it is best when rapt, above paying its respects to anybody's doubt whatsoever. At bottom the world isn't a joke. We only joke about it to avoid an issue with someone to let someone know that we know he's there with his questions: to disarm him by seeming to have heard and done justice to his side of the standing argument. Humor is the most engaging cowardice. With it myself I have been able to hold some of my enemy in play far out of gunshot.
-- Robert Frost, Selected Letters of Robert Frost

I have often observed this in myself. I'd say the majority of my school papers have at least a hint of humor in them. I've long known that humor in social situations is often used as a defense mechanism by some, including myself, but I hadn't translated that to writing for whatever reason.

I love quotations. I like seeing things I already know, myself, elegantly put down on paper.

On a related vein to the above:

The style is the man. Rather say the style is the way the man takes himself; and to be at all charming or even bearable, the way is almost rigidly prescribed. If it is with outer seriousness, it must be with inner humor. If it is with outer humor, it must be with inner seriousness. Neither one alone without the other under it will do.
--Robert Frost, "Hawthorne and Frost: The Making of a Poem." Frost: Centennial Essays

Robert Frost rocks my socks.