There's an old story in my family of my aunt returning home to my grandma's from a bar she lived in the basement, she looked up the basement window and there was some guy naked from the waist down with his wiener hanging and he just started jumping up and down shaking his weiner.
She called the cops and they never found the weirdo.
My question is what kind of power are creeps getting from sick shit like this?
Flashers are a strange societal nuisance of yesteryear. I can't speak to any psychosexual pathology, but from what I've gathered from anecdotes from older family members it was just something that you could encounter living in cities or maybe the suburbs.
As to why? It was always attributed to "weirdos", so probably lots of different reasons ranging from drunk guys daring each other to being mentally unwell and untreated while living on the street. The stereotype is a guy in a trench coat with no pants on who sneaks up on unsuspecting passersby, flashes the goods, then runs off.
I'm sure it still happens but I'd wager that most of people who get a thrill out of it retreated online to sites like Omeagle and Chatroulette. Getting caught can also land you on a registered sex offender list now so I'm sure that has curbed people in the "harmless prank" camp.
Most definitely not the kind of hog posting we endorse here.
My mom has a similar story from when she was around 16. She got home late from a friend's house and once she got in her bedroom, she saw a man standing right outside her window and jerking off. She said her dad had to point a shotgun at his face before he finally took off. It took about an hour for the cops to get there because (rural area in the 70s) and of course by then they were no help. After that, they installed metal bars in all the windows in the house, and got blackout drapes. And my grandpa always kept a loaded shotgun on top of a cabinet in the living room afterwards.