Once a day you can visit your Friends towns and tap up to 3 of their buildings to collect cash and XP. With the Krustyland Update you can also visit their Krustyland and collect tickets! (note: you cannot collect cash from 3 buildings and then collect tickets from 3 attractions at Krustyland. You can ONLY tap up to 3 buildings TOTAL between your friends Springfield and Krustyland per day, greedy pants!)
And don’t worry you don’t need to tap and collect all the money/tickets and XP that come flying out of the buildings, you can just tap the building/attraction and move on to the next town. Like EA magic the money will automatically be added to your account (this goes for the bonus XP you get for visit a friends town and completing 3 tasks as well, even if you leave before you see the box)!