<human>: Throwaway

Today, my GF and I were driving in a busy area of town. At a very busy intersection, a lady and her BF were broken down and were trying to get their car to start. While doing so, the larger looking lady, who was wearing a very short dress, was bent over and we (and the rest of the world) could see her underwear/butt/crotch, etc. My GF asked for my phone so she could take a picture to laugh at later and I asked that we not do that as I felt it was inappropriate. We then got into an argument about this situation. 

Her rationale for the argument is that, and I'm paraphrasing, "Normally...we are both polite, politically correct, kind people. At times, we share inappropriate jokes about others amongst each other. 
Just today we were joking about a robust woman and her lack of neck and then continued to make fun of her clown makeup. Also, we watch EVERYTHING on efukt together. We laugh at people ALL THE TIME but it's just between us."

She finds it hypocritical for me to seem appalled by her wanting to take a secret picture of a woman bent over in a very short skirt with her "Britney" hanging out for the world to see, but be okay with laughing at the pornstars on efukt or the people at Walmart. She states that she "just finds it to be a contradiction to the nature of our humor--especially since we wouldn't be doing it if the person was aware." She feels its okay for me to not "participate" but not okay for me to say she can't. 

Am I being overly sensitive or unjustified?

Give me the gist of the text in a nutshell
<bot>: GF wanted to take a secret picture of a girl in a skirt who was bent over to laugh at later. I feel like it was inappropriate. She feels that that I am being hypocritical.