Paintball was a type of simulated war game, in which combatants used weapons that fired paint pellets, which marked struck targets. It was first developed on Earth in the 20th century, and a forerunner to similar electronic and holographic simulations.
Commander Sonya Gomez joined the staff at Federation Outpost 32 in a game of paintball while awaiting the arrival of a supply ship. During the course of the game, Gomez hit non-combatant Captain David Gold with pink paint, an event reminiscent of the "hot chocolate incident" aboard the USS Enterprise. (CoE eBook: The Art of the Comeback)