Where in London is a place where “green meets blue” that shares a name with somewhere in California?
If you figured that one out, you could have picked up hundreds of pounds today by discovering an envelope stuffed with cash.
It was the latest drop in the Hidden Cash craze that an American millionaire has brought to the UK from San Francisco.
Jason Buzi, a property investor, hit the headlines after hiding tens of thousands of dollars and tweeting cryptic clues.
Some of the 20 envelopes hidden around London, each containing around £100, have already been found.
On Friday, the first clue was tweeted from the Hidden Cash account.
It said: “Large space where green meets blue. Saturday neither early nor late.”
Later in the day, another hint was added to help flummoxed treasure hunters.
“An unincorporated community in Northern California shares its name with our London drop spot,” it said.
Mr Buzi, 43, gave another clue to Sky on Saturday, saying it was the location of a “popular children’s story”.
And for anyone who had failed to guess correctly, the people controlling the Hidden Cash Twitter account gave the game away completely on Saturday afternoon.
“Apparently hardly anyone looking in the right place,” they wrote.
“Kensington Gardens near pond and Peter Pan! There you go! Now get some dough!”
Apparently hardly anyone looking in the right place. Kensington gardens near pond and Peter Pan! There you go! Now get some dough!— Hidden Cash (@HiddenCash) June 21, 2014
Plenty of people obliged, tweeting pictures of the discovered envelopes.
One sleuth found two envelopes and said he would donate the second one to charity.
Mr Buzi is reportedly considering whether to expand the game to the rest of the UK, as well as Paris and Madrid.
Here are some of the lucky winners...