I didn't think this really belonged in the TNG section as it's a more general sort of question but are there any theories as to why Q was so fearful of Guinan?
In the episode Q Who he seemed genuinely afraid of her, and I've always wished they would have expanded on that ..
It probably was those horrid hats and outfits Guinan wore!

Still, it was interesting that Q was afraid of someone he wasn't able to easily wish (or whisk) away to the cornfield at the flick of a finger.