As someone who has a lot of hangups, sexual and otherwise, I agree with the folks saying not to pressure her into anything she doesn't want to do.
I've done it a couple times, I know what it is and that it's not pee, and I'm not embarrassed by it. That being said, I'm disgusted by it. (No offense meant to anyone who is into it, just the way I personally feel when it happens to me.) My orgasms don't feel any different or better. If anything, I just feel nasty afterward.
I guess my point is, really talk to her and find out how she feels (beyond simply being embarrassed) before trying to talk her into it.