Don't try to con your wife into doing anything, if she isn't doing it she has a reason. you should sit down and chitchat with her about why she doesn't do this. If it's because something happened to her at some point and she finds it threatening, leave her alone about it. If she doesn't feel comfortable in her knowledge of it or if she's inexperienced, see if she'd be willing to try, but if she says no, drop it. If she thinks it's gross take a shower with her and do some manscaping. She has a reason, make sure you don't make her feel like she is doing somehing wrong or that she must not care about you because some men have a tendency to make women feel bad when they don't "perform" (I don't know if this works the other way around.

I agree with what Symian says.

The key is figuring out what your wife is concerned about. If it's a religious objection, you need to look at religious writings on the subject. If it's cleanliness, you can shower right before sex. Performing oral sex on her might make her like it and want it and then she might be willing to perform it on you.

If your wife is just shy about it, I think patience and not pushing are the key. Concentrate on making her feel comfortable with you and trusting you. Make sure she is enjoying sex and not feeling pushed. Then eventually she may open up to other acts. It might take a few months or longer, but waiting and then giving her an opportunity again much later might work.

A few tips on oral sex from a male point of view and from a female point of view:

Communication is always key in a relationship. Speaking with your wife about why she refuses to perform fellatio is the first step. If both of you are committed to making each other happy and satisifed, you will be able to find a common ground even if she still ends up refusing to perform fellatio. Be creative, maybe something else may come to mind that will be just as satisifying.