Well, I DON'T KNOW. My jeans are skinny jeans and proper tight around the legs, but they're not exceptionally tight around my hips, even with a belt. For some reason it's still easy to pull the front down just enough. The key is definitely the fact that they're very low, and so pulling the front down just a little bit is enough.
It works for me. I think the way that I urinate is the most organized aspect of my life. Sometimes, it's all that I have.