… are inherently amusing, aren’t they? A second, slightly worse name than your first, secreted away and only brought out under duress, generally to collective titters.
For parents, it’s usually either:(a) a good place to get a bit of familial duty done (grandparents’ names etc); or (b) a consolation prize for daddy in the naming debate; or (c) an early and excellent opportunity to start embarrassing your offspring.
There’s an obvious candidate for Brit Jnr. It begins with a ‘G’.