Boys are considered men once they're baptized.

I once heard a young man tell his mother, “You can't teach me anymore; I've been baptized!” Later on, in a men's meeting, I asked about it, and the others there confirmed this belief: Once a boy has been baptized, his mother (or any other female) can no longer exercise authority over him, since God considers the boy to now be a man. Part of their reasoning comes from Paul's admonition to Timothy:

I do not allow a woman to teach or exercise authority over a man, but to remain quiet. (1 Tim 2:12) NASU

There's nothing in scripture that says a boy suddenly turns into a man at baptism. In fact, it teaches that children are to honor their father and mother. No qualification on age. That would include any advice forthcoming from those parents. Whether or not they heed that advice is another story. The point is, with certain exceptions, parents have authority over their progeny.

I asked these guys in the men's meeting, “So what happens when a young girl gets baptized? Is she all of a sudden a woman?” They became quite annoyed with me at this point.

The point is, certain churches have entrenched male chauvinism in their camps, where women are considered only fit for cooking up the potlucks and cleaning the building. This is unfortunate, and contradicts the New Testament's teaching that there are no longer gender differences in the church. (Gal. 3:28) This doesn't mean women can preach to or teach men. We all have our roles in the kingdom, and no one should seek to usurp someone else's authority. (1 Cor 11:10)