If you want to play a prank, why not do it to people you don't know. Not only will they not suspect a thing, but their reactions can be very funny to watch.
That's the case with this next video tutorial. It shows how to perform the free gumballs prank. All you need to do is attach a sheet saying free gumballs on a gumball machine in the store, mall, or wherever and sit back and enjoy. It doesn't take very long to do and should be enjoyable for everyone around. So good luck and enjoy!