Topknots are standard for both male and female yorkies, and if you ever watch a dog show, you will see that there are no real differences between the sexes when it comes to grooming. Some men do feel threatened by this, and so we usually refer to them as ninja knots instead of topknots.
You can also look at some of the wonderful bows made for male yorkies, Ladymom, a member here, makes some really cute bows with a masculine theme.
M'Lady's Dog Bows - Boy Bows Page 1