What I Wish I'd Said To The Man Who Just Flashed Me

Walking out of my nice, safe apartment in my nice, safe garden-filled neighborhood at 9 am on a Sunday morning with my visiting mother, I ran into a man with his dick in his hands.
He was wearing a striped chunky sweater and looked to be in his late-20s to early-30s. He had a pleasant, if somewhat dopey face. He was standing up against the fence that circles my courtyard, next to the trash cans. If you are going around the corner to pee, like some guys do, this is not that corner. You can either go pee on the wall in the alley by the auto repair, a big blank wall serving as a great canvas for your public urination delight or you go further down this alley where you would be shielded by an actual wall and some large garbage cans. You do not stop on the street and plop your dick up on the ledge of a fence.
We look up at him. We notice his dick is out. Is he taking a pee? What is happening here? He looks at us directly, smiles and says "hi". He then runs from behind us towards the main street. He's wearing jeans. And he runs with the heavy footed clumsiness of a first grader. It's weird.
This is how I did react: I saw him. I looked away. I said nothing. I made sure to get out of there as soon as possible, but not so fast that it looked like I was fleeing. I made sure to show no emotion. I made sure to show no reaction.
I shut down.
I shut down.
I shut down.
As I began to look back on it, was he peeing? Or was he actually jacking off instead? Or was he testing some flashing-lite? The kind you would do before just fully opening your coat in the middle of a road. If he was going to pee in an alley, where he was standing does not make ANY sense. It's in plain view of the entire building and he had a good few minutes to hide himself during the walk from my door to where he was standing. Even if he was just peeing, go around the corner. He chose to be there. He chose not to hide himself when he saw us coming. I feel very violated.
The first thing I did was walk to the flower shop. The opposite direction of where he was heading. Somewhere that I could feel protected. And from there it started to hit me and I began fantasizing about what I could have really said or done, much in the same way that you do after you get into a fight and all the good lines come to you hours later in the shower.
This is how I wish I'd reacted: ARE YOU FUCKING KIDDING ME? PUT YOUR FUCKING DICK AWAY. GET THE FUCK AWAY FROM MY APARTMENT BUILDING. IF YOU DON'T GET THE FUCK AWAY RIGHT NOW I'M CALLING THE COPS. IN FACT, I'M TAKING A PHOTO OF YOUR TINY FUCKING DICK RIGHT THE FUCK NOW AND I AM TAKING IT TO THE COPS.
It aggravates me that in those moments my immediate response is to show no emotion. To shut myself down. To let this aggressor continue their act unaggressed. I want to make him shut down.
As a woman, I don't want the predator to smell my fear. I don't want him to see my reaction and get pleasure from my discomfort. I don't want to show any signs of weakness that would escalate this situation. I want to remove myself from myself. I want to turn myself into the blank shell that these aggressors assume that you are. A blank shell cannot feel. A blank shell cannot be effected. THIS. IS. NOT. OKAY.
Later that day, we were three times approached by a guy just walking the streets who "wanted to ask a question" because "you're so pretty." And I had to repeatedly look down, avoid eye contact and say "thank you, but I'm busy" as I prayed the traffic light would stay green so that I could keep walking.
