The machine sprays the participants with water if they are too slow at taking a chartreuse shot. It is built using an Arduino microcontroller to control a high-pressure water pump and a series of solenoid valves that regulate the flow of water. The system is activated by a button press, which triggers a countdown played on a speaker. If the shot is not completed within the allotted time, the solenoid valves open, releasing a spray of water.