In Star Trek III: The Search for Spock, there is a scene in a lonely transporter room manned (personned?) by Uhura and some no-name lieutenant* fresh out of the academy looking for excitement. As Kirk and the rest rush in in order to make their escape from Earth, Uhura points a phaser at her hapless companion and tells him to go sit in "the closet." Since there appears to be a seat in the aforementioned closet about the height of a toilet for humanoids, I have always assumed this was a bathroom, though it is not mentioned as such for whatever reason--the high moral standards of the 1980s perhaps.

Yes, I am a geek. ========================= *The Internet Movie Database credits actor Scott McGinnis as "Lieutenant 'Mister Adventure' Heisenberg." My apologies.