If I said that I am now the ruler of the world that would be an example of megalomania. A megalomaniac is serious.

Poetic license seems to be similar except everyone is supposed to know you aren't serious. Could I tell you my dreams without you charging me with lunacy? Can I set sail on the ship of words?

If you kiss the Blarney Stone, you are supposed to receive the gift of eloquence. However, it is more likely to be the gift of gab, which isn't the same thing as talking your leg off. This last expression was the way I heard it growing up, but it probably is taken from talk the hind legs off a donkey, and if you consider that someone was telling you that a certain person could talk your leg off, smiling at you, well, think about it. I dislike the expression because, save for one letter, it says taking your leg off, and that opens up an entirely different can of worms.

Does it seem that people use these salty old expressions less these days and are more literal?

Returning to the subject of me being in charge of everything, forget that I said I owned the moon and that, for a good price, I could sell some very nice lots. Joke. But why would I have to explain that? The best things in life are free. There's another song that says "The best things in life are free, but you can keep them for the birds and bees." Take your pick.