(CNN)"Hey girl! Are you alone?"
"I'm gonna come back for you later."
"It'll be so good, you won't want to call it rape."
These are the kinds of catcalls that women -- and some men -- endure on the streets of the world's cities every day.
The problem is widespread. A 2014 study found that in the UK, for example, 90% of women say they experienced their first street harassment before turning 17. More than 70% of South African women say they have been followed by men on the street. Almost half the women surveyed in India say someone has exposed themselves to them.
So women around the world are fighting back. They're documenting actual catcalls they've received by writing them in chalk on streets and sidewalks from Boston to Barcelona, then posting them to Instagram.
What began in 2016 with a single account, Catcalls of NYC, has become an international movement against street harassment. There are now more than 70 related Instagram accounts around the world where people share photos of pavements they've chalked with the words they've had to endure.
"All of the catcalls I post are submissions that have been made to real people in public spaces, most of the time the street, occasionally on public transportation such as buses and trains," said Farah Benis, who founded Catcalls of London.
Organizers of the movement hope the messages -- many of them startlingly crude -- call attention to a global problem.
It's one thing to hear a catcall. It's another thing to see a catcall, tattooed in neon chalk on the spot where the harassment actually happened.
Here's a look at some of them.