Am I an atheist or an agnostic? Well, I would say I am a "Tooth-fairy Agnostic".
I first heard about this term in a TED talk by Richard Dawkins. He was saying about a friend of his:
He calls himself a "Tooth-fairy Agnostic". He won't call himself an atheist, because it's in principal impossible to prove the non-existence of God. But agnostic on its own might suggest that God's existence was somehow on equal terms of likelihood as his non-existence. My friend is strictly agnostic about the tooth-fairy, but it isn't very likely, is it — like God.
Hence the phrase "tooth-fairy agnostic".
Bertrand Russell said about his hypothetical teapot orbiting the Sun:
You strictly have to be agnostic about whether there is a teapot in orbit. But that does not mean you treat the likelihood of its existence as being on all fours with its non-existence.
The list of things which we strictly have to be agnostic about does not stop at tooth-fairies and teapots – it's infinite. If you choose to believe in a particular one of them, unicorns or tooth-fairies or teapots, or Yahweh, then the obligation is on you to say why, not on the rest of us to say why not.
We who are a-theists are also a-faireists and a-teapotists and so on - we just don't bother to say so.