Somebody obviously doesn't have a sibling of the same age range...
Or a daughter who wears the same size.
2 people sharing 1 shirt ..... umm ok
They make shirts like that actually hideyourarms.com/2012/03/29/group-shirts-hya/
But it could just be a business' shirt or a shirt that's part of a band's merchandise (like you would get at a concert)...
chultzatenu lo v'rudah
*vruda, not v'ruda.
only two people? I imagined cuadruples!!!!