Houston, are you ready to stampede the streets? Friday could be your chance to win up to $200 of hidden cash — thanks to acts of kindness sweeping the nation.

It all started two weeks ago when a San Francisco native created the Twitter account @hiddencash, which has now surged to almost 450,000 followers. The account posts random tweets throughout the day, giving scavenger-hunt-like hints to find white envelopes filled with anywhere between $10 to $210. The brains behind the craze, who has remained anonymous, is a real estate mogul who says that after seeing how fortunate he or she was with financial success, wanted to pay back the city and share their wealth.

The series of events starts with a clue tweeted and often vague photo of the location:

Next the crowds swarm the various venues:

And finally the cash is found and tweeted by the lucky winner.

So how did this giver make their way to Los Angeles, Nashville, New Orleans, Dallas, Chicago and eventually Houston? A number of the new giveaway accounts are actually various copycats just trying to spread the love, says the San Francisco mogul on his Twitter account.

Sinceits start, the giving has turned into a two-way street. In exchange for the anonymous cash drops, the Twitter account heads are asking that the cities become inspired to pass the kindness forward by donating toys to local charities, picking up garbage on the beach or even stuffing backpacks for back to school drives.

This phenomenon kicked off in Houston on Tuesday under the account @HoustonHiddenGifts. The mysterious Houston organizer encouraged followers to do such good things as give blood or drop off gifts for cancer patients at M.D. Anderson Cancer Center. (The gift effort fizzled on Wednesday when a number of visitors appeared without advance notice to the hospital.)

Although the Twitter account is still working out some tweaks, the number of followers has jumped by 1,500 to more than 6,000 in the past 12 hours.

While some Houstonians online weren’t very welcoming of the idea, stating that despite the kindness, “nothing is free in life,” the majority has been extremely receptive.

Want your chance to find the cash? Follow @HoustonHiddenGifts or find them on Facebook to get the clues and updates on how you can return the favor and give back to your city.