His artwork has appeared more than 120 times around Boulder.
It’s signed "SMiLE" and often that’s all people know.
People are curious. Many businesses support it, but Boulder Police want to talk to him.
“It's small for what I considered street art,” Stela Knezezic said, who works at Trident Booksellers and Café in downtown Boulder.
“A lot of it is portraits. It feels like an homage to the people who once passed through here,” she said.
Once Knezezic noticed it, she started seeing more, but in places where she least expected.
“Strangely, I saw one on a door. It was a back door to a business. And I was like how did he do that?”
She isn't the only one with questions for SMiLE, who uses spray paint and stencils to create his work in and around Boulder over the last two years.
PHOTO: Artist in Boulder leaves his creations around town
Boulder Police said when SMiLE’s work appears on public and private property without permission, it violates the graffiti ordinance. They added when a code enforcement officer stops to clean it up on public property, they can’t respond to other calls.
It hasn't stopped SMiLE, or so he said over the phone on Tuesday after 9NEWS reached out to him on social media.
“I like putting stuff place where it forces people - surprises them one for moment, one two three five seconds," SMiLE said. "That’s all it takes to snap them out of whatever they are ruminating about and bring them in the present moment. It’s pretty hard to be angry when you are in the present. That’s actually where the name SMiLE originated. That idea of helping people being present and happy."
SMiLE creates his works both at night and during the day and is frank about why he prefers to stay anonymous.
“Partly to protect myself and partly because it’s fun," SMiLE said. "We grew up in my generation reading comic books about super hero, alter egos, anonymous people. It fits into that. It’s fun for me to run around and do it sneakily."
It’s also personal.
“My heart is buried in all four corners of this city. A lot of the choices are personal. I have a spot where my best friend's ashes are spread. I put up a couple in the area I knew she would like,” SMiLE said.
SMiLE is ready to keep doing this as long as it feel right. In fact, he’s planning to go back out and do more work later this week.
He did get the message from police over the summer and is staying away from some public areas. Boulder Police say they haven’t had issue with SMiLE’s work on public property since the summer.
Police did say if his work appears on private property, it’s up to the owners to decide if they want to remove it.
The Downtown Boulder INC, that works with several hundred businesses, said so far they’ve only received one complaint.