The "hidden cash" phenomenon that's been causing a social media frenzy in the San Francisco Bay Area has spread to Boulder, where an anonymous group started hiding money around town and tweeting out clues via the @HiddenCashCO account Wednesday afternoon.

The group hid the first batch of money behind the St. Julien Hotel & Spa downtown inside the basket of a Boulder B-cycle bike.

The first clue that was tweeted: "It's our very first clue! See our town in red, white, and blue. Two wheels will make you wise. In the bottom of a basket, find the prize."

The group tweeted increasingly revealing clues about the location of the money.

Matt de Caussin arrives too late to get the money hidden in the basket of a B-cycle bike basket in the bike racks just east the St Julien Hotel & Spa in
Matt de Caussin arrives too late to get the money hidden in the basket of a B-cycle bike basket in the bike racks just east the St Julien Hotel & Spa in Boulder on Thursday May 28, 2014. de Caussin said he was only a block away when the tweet came through with a photo that indicated which bike rack had the hidden money. Photo by Paul Aiken / The Boulder Daily Camera / May (Paul Aiken)

That cash was found by accident by Marni Ratzel, who rode off on the B-cycle bike and found the money when she arrived at her destination. Matt de Caussin walked up to the B-cycle station minutes too late, peered into the baskets of two remaining bikes, shrugged his shoulders and walked away.

Ratzel, city of Boulder bike and pedestrian transportation planner, said she was completely surprised when she looked down and saw the envelope.

"It's totally random that I found it," she said. "But it's also great that it happened while I was on a B-cycle, as far as I'm concerned."

A second envelope was found Wednesday afternoon by Josh Montague in front of the Flatirons Bank at 11th Street and Canyon Boulevard. It contained $40.

Montague said he planned to go buy a batch of cupcakes to share with his coworkers.

"It's fun," he said. "If you have the opportunity to scoot out for 60 seconds during the day, then it's cool. If you've got a few dollars to throw out and people can have a good time, that's pretty fun."

In San Francisco, an anonymous man with the Twitter handle @HiddenCash has been hiding money throughout the city since Friday, leading scores on a scavenger hunt. His Twitter following exploded from a few hundred Friday to more than 80,000 and counting by midday Tuesday.

Hidden Cash's anonymous creator said his giveaways are a "social experiment for good." He claims to make his money off San Francisco's hot and lucrative real estate market and hopes that winners also "pay it forward."

The Boulder group spoke to the Daily Camera on condition of anonymity because they didn't want any one person to be identified as responsible for the game.

The group said it was inspired by the original Hidden Cash movement and thought something similar would be fun in Boulder.

"It's great to promote happiness and get people to enjoy life a little bit," the group said.

The Associated Press contributed to this report.

A photo of an envelope hidden in a Boulder B-cycle bike basket near the St. Julien Hotel & Spa on Wednesday.
A photo of an envelope hidden in a Boulder B-cycle bike basket near the St. Julien Hotel & Spa on Wednesday. (Courtesy @hiddencashco)

Contact Camera Staff Writer Sarah Kuta at 303-473-1106 or kutas@dailycamera.com.