Some people drop them. Others leave their mobile phone on the roof of the car and drive off. Or they slip the device into a purse or pocket - and miss.
Whatever the cause, smartphones with cracked screens seem to be nearly as common as cellphones themselves. The phenomenon - particularly frequent among the glass-cased iPhones - has prompted repair services to mushroom at mall kiosks, computer shops and college campuses.
Over the course of a year, nearly a third of iPhone users damaged their device, according to the results of a survey released last September by SquareTrade, which sells protection plans for electronics. Owners spent $6 billion in the previous six years to repair or replace phones that had been cracked, dropped, kicked, waterlogged or otherwise damaged.
And it's not just the iPhone. Consumers have spent well over $7 billion on damaged Android phones since 2007, SquareTrade said in April.
"It's not a malfunction. It's not the product's fault. It's the klutz in us," said Jessica Hoffman, a spokeswoman for SquareTrade, which she said covers accidental or lifestyle damage, such as "my son threw it in the bathtub" or "my pet tripped over the power cord."
At some shops, screen repairs on certain iPhone models start at $70, a cheaper alternative than buying a new one, which can cost $400 or more.
Apple discourages consumers from going anywhere other than an Apple store or Apple-authorized center to avoid voiding warranties. New iPhones come with a one-year warranty that covers two incidents of accidental damage, for a $49 fee each time. Consumers can pay $99 to extend that warranty for an additional year, again to cover two accidents for a $49 fee each time. Once warranties expire, repairs to damaged screens run from $149 to $299, depending on the model.
In March, iFix2Go set up a kiosk in a corridor at Towson (Md.) Town Center mall, where technician Kendal Robinson fixes some of the more than 100 phones and tablets that come in for screen repair each month.
"There's high demand because a lot of people are ineligible for a (phone) upgrade, and they don't want to pay the substantial fee for a new device," Robinson said. "This is an option to get it repaired and reuse the same device."
Consumers who drop off an iPhone 4 at the iFix2Go kiosk can expect to pay $100 for a new screen and get the phone back in an hour or less. A screen on an iPhone 3G costs $50.
A subsidiary of GreenLoop IT Inc., a technology company with businesses that extend the life of IT equipment, iFix2Go repairs iPhones, iPads and iPods in one hour or less. The kiosks have been opening in shopping malls, train stations and business conference centers. The company said its seven kiosks in four states repair more than 1,000 devices a day.
Robinson said he has seen it all, including the customer who left an iPad on top of her car then ran over it.
In a case like that, he said, "it's fixable but not guaranteed to be fixed."
Even when a cellphone is cracked but in working order, "it can be complicated," Robinson said. "It is time-consuming. You have to tear down the phone, meaning take off all the parts that make the phone work."
At PHD Fix, a computer repair shop that opened last October in Lutherville, Md., technicians repair three to five cracked screens a day.
"They are made of glass, so the glass is easily cracked," said Daniel Huang, an employee.
Those who tend to damage the fragile iPhones the most - teens and college students - are often the least able to afford a repair or replacement. They are looking for low-cost alternatives.
That was the market Harrison Baum went after when he started onCampus Repairs at the University of Maryland-College Park more than a year ago.
"Whoops. You dropped your iPhone," the service's website says. "That's cool though, we can fix that! Actually, we kinda like doing it."
Baum, a senior economics major, describes himself as a tech "nerd" with a knack for taking apart and rebuilding devices. He'd taken his own damaged iPhone apart to fix and noticed he was far from alone.
"When I got to college, I saw cracked phones everywhere," said the 22-year-old Rockville, Md., native, who bought damaged phones on Craigslist to perfect his technique. "Every other person had a cracked screen. I kept fixing them, and more and more people kept breaking them and coming to me."
He now fixes 50 to 70 cracked smartphones a month, catering not only to students but faculty, too. Some of his customers tried to fix the phones themselves first.
Baum charges $70 to replace the screen on an iPhone4 and iPhone4S, and said he keeps his cost low because he works out of his campus apartment and does most of the work himself. He completes most repairs in a half-hour or so. His parts come in large shipments he orders wholesale from China.
"I'd be pulling all-nighters and going to class the next day," said Baum, who expects to graduate in December then focus on his business full time.
Now he's branching out, buying old or broken phones that he repairs and resells through a spinoff business called SellMyOldTech. He runs that from College Park and will start up a service this fall at Salisbury University in Salisbury, Md.
Julian Capps was a University of Maryland senior with a cracked iPhone 4 last year when he found his way to onCampus Repairs.
"I dropped it on the sidewalk," Capps said of the cellphone he'd prided himself on protecting. "The screen did that shatter thing. I knew I'd have to go to Apple and pay hundreds to get it fixed."
But he didn't.
"I just sucked it up and lived with it," said Capps, 23, now working for a software startup in Boston. "None of the functions were affected. My plan was to live with it. There was no way I was going to pay a couple hundred dollars."
Then he heard from a friend about Baum's service, booked a repair online and met Baum near campus to drop off the damaged phone. Less than an hour later, Baum returned with the repaired phone.
The phenomenon of college students with beat-up cellphones was the subject of a video spoof by The Onion in December, a "report" that Apple had unveiled the first ever iPhone geared specifically toward college age girls. The thinner, lighter version of the iPhone 5, the spoof video went, comes with a broken screen, "already so shattered you can barely read anything or dial half the numbers."
The satire has some elements of truth. Baum, like Robinson, has inspected several smartphones run over by cars. (Sometimes those can be fixed as long as the motherboard is not damaged, he said.)
Then there was the student who picked up her repaired cellphone from Baum, tried to put it in her purse and dropped it on the floor. She left the phone, with newly shattered screen, with Baum for a second time.
He recalled her saying as she left, "You're going to tell everyone about this, aren't you?"
Explore further: Review: Samsung Galaxy S6 impresses, but something's missing