Authorities say 20 students from Danbury High School have been issued $103 infractions for creating a public disturbance when end-of-year senior pranks went awry.
The pranks, which started Friday morning with water balloons and Silly String, escalated when students filled plastic foam cups with water and placed them in the freshman hallway.
Students tweeted that "DHS" was "going wild" and got "reckless" throughout the day.
"Its the last day of school and everyones going crazy," one girl tweeted.
As the day progressed, school officials say, students started tossing water and a melee broke out in the lunchroom.
Nobody was injured, but police were called to quell the disturbances and up to 25 students will face five-day suspensions for the pranks.
Any seniors who took part will be prohibited from participating in graduation ceremonies next Friday.