Turns out it is an event. It's pretty much the same as snowball fight. It seems to have a few bugs though, I've joined twice and gotten in both times, each time I haven't been able to play. The first time the game seemed to have froze and it never started. Players were stuck there and we all had to unstuck me (\leave did not work). Second time, the game did start, but my screen was all black, I could not move or throw balloons, and all I could see was balloons flying around. I couldn't see the other players. I was getting hit with balloons and losing no health. Somehow I ended up winning I think it's because the other team just left lol. I can assure you I was not lagging, my ms was probably like 87.