How come Bonnie, Ronnie and Lonnie are okay names, but Nonny for some mysterious reason is not?

And what about the Greek singer Nani Mosquiri? (sp)
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Here's a different aspect of name-giving. I recently went to a softball game played by ten-year-old girls. Here are some of their names:

Hayley
Bailey
Mason
Bob (christened Megan)
Madison

Why do I get the feeling that their parents wanted boys and are not ashamed to let the world (including their daughers) know it?

The exception might be Hayley, whose name was probably inspired by the indubitably female Hayley Mills.