Cryptic tweets lead to free cash in San Francisco

A mystery Twitter user has begun a "social experiment" by giving away envelopes stuffed with cash to residents of San Francisco.

Over 115,000 people are now following @HiddenCash for cryptic clues about where the envelopes have been stashed.

The secret philanthropist has cast the net wide, leaving money all over the city, including on the beach, attached to palm trees and even in a restaurant toilet.

The account has taken off so quickly that the anonymous user has confessed to being "a little overwhelmed with requests for media and cash".

Such has been its popularity that this morning the mystery user extended their generosity to the neighbouring city of San Jose.

And it has not stopped there - apparently next weekend the freebies will start popping up in Los Angeles.