In 2267, the USS Enterprise put in to Cygnet XIV for general repair and maintenance. During the overhaul, the planet's inhabitants, deciding that the ship's computer lacked sufficient personality, modified it with a female one. This caused some annoyance to the crew, especially Captain Kirk, whom the computer often addressed as "dear", and Mr. Spock, who noted that the computer had "an unfortunate tendency to giggle."
Spock explained the computer's odd behavior to John Christopher when the pilot briefly visited the Enterprise that year and witnessed its amorous interactions with Kirk. (TOS: "Tomorrow is Yesterday")