If someone ran up to you in the middle of the day with a phone and asked you to answer the call, would you?
How about if the person on the other end of the phone asked you to pick up a manilla envelope from a stranger?
Well, this was the predicament faced by unsuspecting parkgoers recently when actor Matt Damon recruited them on surprise spy missions, as part of a prank in partnership with Omaze charity to raise money for Water.org.
The Ocean's Eleven actor, who is well-accustomed to secret operations after playing the titular character in the Bourne franchise, had random men approach strangers, passing them a mobile phone and instructing them to 'answer the call'.
When they answered, Damon was on the other end with a set of instructions, ranging from telling one to buy a hotdog to another having to say 'Elephants can swim' to a bystander, much to Damon and the camera crew's amusement.
The unwitting strangers were then told to enter a car park office and await further instructions before Damon made the big reveal, surprising his new 'recruits' with tickets to the Jason Bourne premiere.
Watch the hilarious video here:
Jason Bourne opens in UK cinemas on 27 July.