It is one of the two Summer contracts, along with Getting Ready which began on the 20th of June, 2018 and is valid for 28 days, twice as long as Getting Ready.
The contract was put up after Waterballoon Eggs were created, presumably for fun, then the idea to mass-produce them for water balloon fights was started.
The contract can be challenged by up to 6 players with a time limit of 4 days.
"The longest day of the year is here (norther[sic] hemisphere) and you know what that means!"
- Deliver 75t WATERBALLOON Eggs
- Reward: 621 Golden Eggs
- Deliver 500t WATERBALLOON Eggs
- Reward: 500,000 Soul Eggs
- Deliver 4q WATERBALLOON Eggs
- Reward: 1 Egg of Prophecy
- The description contains two mistakes; June 21st is not the longest day, but rather has the most daylight and 'northern' has a typo.