Wild Hares or Hairs?

The blogger at Anarchy In The AK comments yesterday about an ADN report on the surfer who got pulled out with the tide in Turnagain Arm.

What the ADN fails to mention is that Paul is not just your casual dip-shit that gets a wild hare up his ass and decides to go surf the bore tide.

OK, I have to be careful all the time that I don't write 'their' instead of 'there' or 'its' instead of 'it's' so I'm not casting stones here. But it made me think, "It is 'hair' isn't it?" And what the hell does it mean anyway?

Daily Writing Tips has this discussion:

DWT reader Jess received an email in which the sender said “I got a wild hair about me.” Jess says that the expression was used in the sense of acting impetuously.

However, the expression for which “wild hair” is a shortening is “to have a wild hair up one’s ass.” The meaning of this vulgar expression is “to have an obsession or fixation about something.”

Garrison Keillor conveys this sense in his August 2, 2008 News from Lake Woebegone segment. In this instance it’s not a hair but a quarter, and it’s not up anything, it’s between the butt cheeks. He’s talking about a woman who is very angry about something and is going to confront her brother about it:

…she stalked across that farmyard like somebody who’s carrying a quarter in their butt. If you go around carrying a quarter in your butt, you won’t think of anything else.

Disagreement exists as to why a hair should cause such single-minded discomfort, but I suppose there could be such a thing as a painful ingrown hair. The word “wild” in this context refers to the fact that the hair in question is not going where it is wanted.

The meaning implied in the email, “to act impetuously or in an uncharacteristic manner,” doesn’t seem as apt.

The comments at the end suggest

• common use of the idea of a spontaneous act
• no agreement on hare or hair
  

and a reference to Kevin Drum's discussion of some Google results in A Wild Herr.