But few have seen anything like Friday's "Batkid" phenomenon, which melted even the hardest of hearts and had people across the country weeping onto their computer keyboards at work.
Dozens of people tweeted about being overwhelmed by emotion while reading about Miles Scott, the 5-year-old leukemia patient who dreamed of being Batman. The Make-a-Wish foundation granted his wish by working with volunteers and local leaders to turn San Francisco into Gotham City for a day.
Miles' cancer is in remission, and he finished his treatments in June.
On Friday, Twitter users wrote about fighting back tears at work, at the dentist's office, at the airport and elsewhere as they read about how Miles rescued a damsel in distress, thwarted a bank robbery and was given a key to the city by Mayor Ed Lee.
"I've been crying about batkid all morning. Sometimes humans get it right," one user wrote.
Another tweeted, "The Batkid story has me crying off all my makeup. Worth it. High five, San Francisco."
The teary tweets kept coming over the weekend.
"Resisted for days not reading the Batkid story, just finishing it now," one person tweeted on Sunday. "I'm not crying, I've just got something in both my eyes."
San Francisco police Chief Greg Suhr said today, "It was really unbelievable. The best part about it is, although the little guy had to get sick to get better ... there was no catastrophe, nobody had to die for all these people to show up to spectacularly support his victory."
Suhr noted that the story has been reported across the country and the world, including in Kathmandu, Australia, Switzerland and Iran.
Even President Obama congratulated the pint-size superhero in a video message, and so many donations poured in to the Make-a-Wish foundation that its website crashed.
Suhr said that when asked to participate in the Batkid festivities, he agreed without hesitation. He said organizers initially hoped to get 500 volunteers to cheer Miles on at his "hero's welcome" at City Hall.
Instead, word spread like a prairie fire through social media and thousands flocked to San Francisco to support Batkid as he thwarted evil plots by the Penguin and the Riddler.
"I just keep reliving the day ... I can't ever remember a moment in time that's better than that one. This is the best city," Suhr said.
Miles, too, has a pile of happy memories to keep him company.
Suhr said the young hero's father, Nick Scott, told him that as soon as Miles' parents put the cape on him Friday morning, his shoulders went back and he took the fist-clenched stance of a bodybuilder.
"He was on duty," the chief said.
Some 5-year-olds might have shrunk in the face of such intense attention and big crowds, but not Miles.
"He was diagnosed when he was 20 months old and all he's ever known is a tough road ... A little bit of a crowd? No problem," Suhr said.
Suhr said he was sitting next to Miles at City Hall when the theme song from the original Batman TV series of the 1960s came on.
"He was kind of rockin' it, and I go, 'Do you know this song?' and he just looks at me and he goes, 'It's my song,'" Suhr said.
Suhr's own son Matt got in on the action, designing a "Batkid" T-shirt for Miles' fans to wear, with proceeds going to Make-a-Wish. Just like everything else related to Batkid, the T-shirt idea took on a life of its own.
Demand for the shirts was so high that the Kid Monarch Clothing website where they were being sold crashed, and Suhr said his son is now fielding a request from someone in Europe to use his design there.
No police overtime was required on Friday, and no city funds were spent on the staging of the Batkid events, Suhr said.
Police spokeswoman Sgt. Danielle Newman said everything went smoothly and no problems were reported.
"This was a feel-good event. People came here to really do something positive. You didn't really have anyone in the crowd acting out, doing those negative things that we sometimes see in large celebrations," she said.
Suhr said he hopes San Francisco did justice to Miles' wish -- and he is asking the 5-year-old to keep the city in mind if he decides to go pro with his crime fighting someday.
"I'd love to have him as a San Francisco cop," Suhr said.