Judging from the responses, women don't really appreciate being forced to look at someone's junk. Some might be a bit prudish about it, others might actually enjoy it more than they let on, but unwelcome genitalia usually results in negative responses. One could probably equate that to being flashed by a guy wearing nothing but a trench coat in some cases. Understandably, not pleasant and probably changes your entire perspective on guy.
There is a subtle way though...
So you're out to dinner or just having some coffee...show her a funny video/picture on your phone, leave it in her hands and make your way to bathroom. She'll have a quick look-see (I'm willing to bet money, or maybe it's just my bad taste in women) and stumble upon revealing pictures that I've intentionally left for her prying eyes.
HA! Take that, women.
Just kidding, I'm not that slick.