An anonymous San Francisco millionaire with a fortune in real estate money is unloading some of his cash across town in a stunt that has quickly become an online sensation. The unseen proprietor of @HiddenCash on Twitter has given away over $4,000 since last Thursday by tweeting clues directing people to envelopes stuffed with $20 and $100 bills.

Hidden Cash started with next to no Twitter followers on Friday, but that number quickly shot up to over 72,000 by Tuesday morning after the account started getting a ton of coverage everywhere from the Chronicle to USA Today. As the generous guy told the Bold Italic, he has made millions of dollars in real estate deals over the past few years, but feels bad that other people can barely pay their rent in the Bay Area. Hence the idea to give away a tiny portion of his earnings, one cash-stuffed envelope at a time.

"People complain that the price of real estate here is pretty high and I have benefited from that," he explained to ABC News. "I wanted to do something fun for the city of San Francisco, something that would get people excited."

So far, Hidden Cash has been unloading about $1,000 a day in $100 increments, a number the man says is "definitely manageable." The tweeted clues read like little riddles and often feature sideways photos of the drop site. Now that the phenomenon has caught on, scavenger hunters are starting to face some competition as they scramble to get to the bounty first.

The man says he would like to remain anonymous because he has, "had some publicity before and nothing good ever resulted from it," but now that San Francisco has been benefiting from his generous nature, he also plans to take the treasure hunt nationwide. He says he will be dropping money in San Jose this Wednesday and heading to Los Angeles next weekend and to New York in the future. In addition to the funds he shares with his Twitter followers, @HiddenCash says that he also supports "many charities" and he hopes that everyone will use the cash and pay it forward.