Doonesbury by Garry Trudeau for April 20, 1972
Nichole: Gentlemen; you are witness to this thin white line which sister Didi has drawn down the middle of the house. Anybody who tries to cross that line into the women's quarters past nine o'clock will be fined fifty dollars and asked to leave the commune. Good night. Mike: You know, this isn't working out quite like I'd hoped.