The CDU party chief and likely future conservative candidate for the chancellery, usually dubbed just AKK because of her tongue-twister name, made the joke in a carnival speech last week.
Attempting to poke fun at politically progressive Berlin, she said newly introduced toilets for intersex people were “for those men who don't know whether to pee standing up or sitting down”.
The comment was greeted with jeers, fanfare and booming laughter in the Lake Constance town of Stockach in southern Germany, but fewer people were laughing when it was shared on the website queer.de and Twitter.
“Another one of those days that make you cringe… is it really that difficult to make a humorous speech without flat jokes beating up on minorities?” commented lawmaker Jens Brandenburg of the FDP party.
Similar criticism rained down from MPs across party lines on 56-year-old AKK, the former premier of the tiny state of Saarland.
The Social Democrats' general secretary Lars Klingbeil charged that the comment showed “an absolute lack of respect” for intersex people, whose legal status was only formally recognised in Germany last year.
The newspaper Kölner Stadt-Anzeiger in Cologne, a city at the heart of Germany's carnival tradition, slammed AKK's joke as “low-brow”, “sordid”, “populist” and tapping into society's “culture wars”.
AKK, a devout Catholic who has spoken out against same-sex marriage, was named “Miss Homophobia 2018” in an online poll conducted by gay and lesbian rights group Enough is Enough.