Maybe a more... universal example should be given: you know those girls at Beatles or Elvis concerts in the 60's who literally fainted from excitement? That is a fangirl. Fangirls use (and overuse) expressions like OMG, squealing with delight, *I'm descriptive asterisking,* O.o (an expression of confusion), XD (an expression of excitement), and the plethora of emoticons.
Let me give you Wikipedia's definition of fangirl:
The term fangirl can be used to describe a female member of a fandom community (counterpart to the masculine "fanboy"). Fangirls tend to be more devoted to emotional and romantic aspects of their fandom (...). However, it is commonly used in a derogatory sense to describe a girl's obsession with something.
What has brought on this definition, you ask? I was thinking about yarn.
I was thinking about yarn, and how, while I love it, I don't ever say, "I have to have that skein of Prism, and damn the expense!" or "I know you're allergic to rabbits, but I got you this LL Angel because it's so fluffy." or "That yarn show is going to be packed, but I will fight anyone who gets in the way of my Koigu!"*
I was also thinking about patterns. When I finished my Jaywalkers, I thought, "Yeah, that was a neat pattern," not "I have got to blog about my love for this right now!" (In fact, I haven't posted any pictures or talked about it at all.) I don't look at Alice Starmore patterns, and think that they're way cool because Alice Starmore designed them. I don't ever insist that Clapotis is the new poncho (or whatever), or that people who haven't made it are "missing out" (I'd be one of those people, anyway).
My point? Uh... Oh yeah! My point is that I am not one to exclaim exuberantly and at length about an item, in general. I am not, in most cases, a fangirl.
For Cookie A of Pomatomus fame, I am.
I occasionally write comments on her blog- and I do that for almost no one- I've visually fondled the different patterns she creates, and her love of Louet Gems has me convinced of the yarn's excellence. I hope to eventually create as cool patterns as she does, and keep enough patience to knit complicated cable & lace socks. Like a good fangirl, I enthuse about these things to people who a) have no idea what I'm talking about, and b) don't care. I also squee quietly to myself when she posts about a new pattern.
At Stitches West, where Cookie has a booth, I will buy all her patterns (and I never buy individual patterns- I'm too cheap), some of her handpainted yarn (oh my god- I'm squee-ing this very moment), and I will be too nervous to talk to her unless spoken to first. (In the event of conversation, I will half-mumble polite answers, but not strike up a conversation, and then kick myself later.)
I do and feel all this for no one. Seriously, I've been too miserly to even buy Eunny's patterns off her blog. And I love Eunny.
So you see? I am a fangirl for a sock designer.
*This gave me a humorous mental image of "Two men enter, one man leaves" from Mad Max: Beyond Thunderdome.