In this report:
http://www.straightdope.com/mailbag/mmulligan.html
Sam claims “Indian Summer” is “an ethnic slur.” But in this thread:
http://boards.straightdope.com/sdmb/showthread.php?threadid=85989
some obnoxious twerp actually opens a dictionary and finds “origin uncertain,” and proceeds to offer an alternate, more convincing etymology.
The nerve of some people…
– Beruang
Beruang You’re getting ahead of yourself. Could you please wait until you have read my critique of the mulligan thread until you try to link it to something I said about “Indian Summer.” 
Seriously, your first link is to the “Mulligan” thread. I’m sure you meant a previous thread where I said something stupid.
I searched but can’t find it easilly. Could you relink?
Yeah, Beruang.
I wonder how that constitutes a slur.
Guess I blew it. It never occurred to me that the staffSam had used the term “Indian Summer.” In my haste, I thought that you(Beruang) were referring to me(samclem) and something I must have said in one of our old threads about Indian Summer.
Beruang. Your link to the Random House site in the previous thread was clear—origin uncertain. One of the theories that they recount is Mencken’s that it was an ethnic slur.
If you mean that your theory is
, I would probably take your side. But, again, your theory is as proveable as Sam’s.
StaffSam errs in implying that there is a generally-accepted etymology for “Indian Summer.” While the notion that Indian summer derives from the notion that such weather is offered only to be taken away (as in “Indian giver”) is seen as one of the more likely possibilities, the possibilities that the phrase comes from a belief that Indian summer weather occurred principally in Indian-held lands or during a time of the year in which Indians had more contact with white settlers (i.e., brought their crops to market) are also considered viable.
Sean