>This is probably a good example of the fallacy that says that if I can do it anyone can.
It is unfair to accuse twosleepy of a fallacy, because it rather depends on what twosleepy was trying to prove. Any unconditional postulation, such as, "It is impossible for an adult to A" is falsified by a single exception. twosleepy does not claim that, "It is easy because I did it"; but simply, "It can be done because I did it." I don't see any fallacy here. (I can't comment on the "Golden Rule Fallacy" however, because you waggishly choose not to define it).
twosleepy, tell us: What language did you master and when did you start learning it?
I can see that what twosleepy said was not that anyone can do it and I apologize for suggesting that she had committed a fallacy here. I took it a little more generally than that and I see that I was wrong. There was a little of the generic to her "Adults can, and do, learn another language to (near) native fluency. I did."
As for the Golden Rule Fallacy, the Golden Rule states that one should do to others what one would want done to oneself. The problem here is that the others may not want done to them what you would want done to you. The assumption is that the others are like you. In some cases it will be true, but certainly not always.
Edit:
Oh, and the original claim was not that no adult can become fluent in a second language, merely that it is rare; one counter-example would not disprove it.
