Sort:  

Its funny because of irony.

Verbal irony is a statement in which the meaning that a speaker employs is sharply different from the meaning that is ostensibly expressed. The ironic statement usually involves the explicit expression of one attitude or evaluation, but with indications in the overall speech-situation that the speaker intends a very different, and often opposite, attitude or evaluation.

The irony here is that the point you were trying to make (being called "sir" seems odd to you because you are a woman), is at odds with the example you used, since "Starbuck from battlestar Galactica" could either refer to a man or a woman, depending on which series the reader is familiar with.

That is to say, you illustrated incongruity of the posters implicit misidentification of your gender with an analogy that was subject to precisely the same misidentification.