And, authorities said Thursday, they did. Eight cases have been reported in four states in recent days, and authorities say felony charges could be filed against whoever is making the calls.
In Alabama, a Marine roused from his sleep got "knocked silly" by a blast of water after being persuaded to set off the sprinkler in his room; there was no fire.
A motel in Arkansas sustained $50,000 in damage when a worker fell for a similar ruse.
A man was even convinced to drive his truck through a door of a hotel lobby in Nebraska, supposedly to turn off a fire alarm. And in California, a duped worker activated a sprinkler at the front desk, dousing computers, phones and other electrical equipment.
"It's happening all over," said Fire Marshal Ed Paulk of Alabama, where four hotels have been targeted by the calls since last week, resulting in thousands of dollars in damage. "We're actively trying to track this and find out who is doing this."
The general manager of a Comfort Suites in Daphne near the Alabama coast, Rupesh Desai, said a prank call about a fire alarm resulted in $10,000 in water damage last Friday.
Around the same time, he said, a caller convinced guests to bust windows at a sister hotel in Saraland, about 25 miles away, because of a natural gas leak that didn't exist.
"In my hotel experience I've never heard of anything like this," Desai said.
Trying to prevent more people from being fooled, trade groups are telling member companies and hotels to remind workers about basic emergency procedures like calling managers or security companies before doing anything drastic like setting off fire suppression sprinklers.
"No employees should be doing things like this without checking with someone," said Namara Mercer, executive director of the San Diego County Hotel-Motel Association in San Diego, Calif.
Paulk said investigators suspect more than one person is behind the calls, and some could be inspired by Internet sites about phone pranks.
In York, Neb., Police Chief Don Klug said a man with a deep voice phoned a Hampton Inn around midnight on May 27 and scared a desk worker into pulling a fire alarm. During the confusion, the caller then convinced the worker the only way to silence the noise was to break lobby windows.
"A trucker was standing there, and he offered to help and drove his truck through the front door," said Klug. The damage was estimated at $300, he said.
Desai, the Alabama hotel manager, said seven rooms were flooded when a caller got the sleeping Marine to set off the sprinkler in his room.
"He was knocked silly by the force of the water," said Desai. "He was not a dummy, he just woke up in the middle of the night not realizing what was going on."
Six other guests also got the calls but did nothing, he said.
A couple hours later in San Luis Obispo, Calif., a worker caused major damage by following a caller's instructions to activate a sprinkler at the front desk of a Comfort Inn and Suites.
And in Conway, Ark., a caller convinced a worker at a Holiday Inn Express to set off an audible fire alarm and, with help from a guest, broke windows in an attempt to turn it off. She also was duped into turning on a sprinkler, flooding the lobby and causing major damage; about 150 guests were in the parking lot when police arrived.
A Holiday Inn Express in Little Rock, Ark., got a similar call around the same time, a police report said, but no one fell for the prank there.
The Alabama fire marshall said whoever's making the calls could face jail time.
"It's gotten to be the latest fad, but at some point someone is going to be caught," he said.