Before your boyfriend goes down on you, there'll (hopefully) be lots of foreplay (you know the deal). This will allow vaginal juices secretion and these juices smell VERY different from urine (also taste different - haven't tried, have asked). Guys love their smell and most guys like the taste too. My bf loves both. So all you need to do to kill the smell of urine (the BAD smell, that is), is make a loooong foreplay so that you get "wet" down there,get it? Then things will smell TOTALLY different from normal. You can prolong the foreplay by nibbling on your man's ears, stroking his butt etc. He'll love it and you'll get your blow wihtout being ashamed.