In the other languages I know it's called 2 bedrooms with a common bathroom. I agree, it's longer to say than just a Jack and Jill bathroom.
I tried to find out the origin of this expression. No way, even Google didn't know. They all refer to an English nursery rhyme :
Now what the heck this rhyme has to do with a bathroom ? I tried to find out who invented the Jack and Jill bathroom, but apparently nobody knows !
The best answer I could find was : It is called that because it is a bathroom that adjoins two bedrooms -- generally separating the two. And the most common gender in families with two children is one male and one female. Hence, the bathroom usually separated a girl's bathroom from a boy's bathroom. And the original designer of the first J-and-J bathroom had 2 kids -- one named Francis and one named Mervyn." Which still doesn't say why is it called Jack and Jill instead of Francis and Mervyn ?
Even Wikipedia let me down it says : On entering the bathroom, one should lock the opposite door to prevent entry from the other bedroom. Before leaving, that door should be unlocked and the other door locked from the bedroom side. This will then allow occupants of either bedroom to use the bathroom, but not gain access to the other bedroom.
If full privacy is not required, for example to wash one’s face or brush one’s teeth, the opposite door need not be locked. This would allow the other party to make simultaneous limited use of the bathroom, especially if it contains a washbasin for each bedroom.
Does someone know the answer ?
more participants at Jenny Matlock's Alphabet Thursday