The Red Ball, is an object that was obtained from the Happy Red Gift of Fun, which was available from December 17th until December 25th, 2015. This ball has a unique number that is obtained upon opening the Red Ball. Unlike its counterpart, the Blue Ball, it is red.
After the gifts were opened, a player asked Defaultio about the purpose of the ball. He claimed that it was an economic experiment to see if players would trade for special numbers. Currently, at least one player has at least 2 red balls with the same number. The ball number continues to increase every day. Learn more about the red ball here.
The red ball can be used for mini golf. What you do is roll the ball so that it rolls into a hole, but if you miss it will go into another pocket at the back which will count as a miss. The ball can also be used as a basketball when playing pumpkinball, but this isn't done often as most people prefer to use the Pumpkin.