My favourites, Bilbo and Pippin, were rejected by Mrs Saucepan. Although, she was the one who decided upon Frodo (something to do with his big, heart-melting eyes when she picked him up).
I was toying with the idea of something in Elvish but the variants for "Black Dog", Morhû and Hûmor, somehow didn't sound appropriate. But you might try an Elvish translation of something suitable (I wonder what the Elvish for head-butting captain is?
).