Hi, 'For free' has been said so often and for so long that I think some people would say it is now standard. Other people still wince on hearing this phrase.
Oh Newguest - that is so funny! I am still laughing! If I went to the shoe store and they said, "If you buy this shoe, you get another for free," then I would have to think if I wanted a left one or a right one.Maybe it would be a good deal for a one-legged person, but they would have to find another one-legged person of the opposite variety.