"...It was ...fun. ...Oh my."
Fun was the feeling of enjoyment or entertainment from an activity, and was typically associated with recreation.
In 2268, Captain James T. Kirk told a group of orphaned children on the planet Triacus that it was late and time to go up to the USS Enterprise. The children were displeased as they were just beginning to have fun playing. After getting ice cream from a food synthesizer inside the arboretum aboard the ship, a child responded to Nurse Christine Chapel that it was fun to get ice cream out of a computer. (TOS: "And the Children Shall Lead")