Who says they don't exist. They exist in the underworld. Same places as fairies, gnomes, etc.

What do you mean - if?

I would get busy making little half-Leprechaun babies! I'm a sucker for Irish accents.

Leprechauns rarely appear in what would be classed as a folk tale; in almost all cases the interest of these stories centres round a human hero. Stories about leprechauns are generally very brief and generally have local names and scenery attached to them. The tales are usually told conversationally as any other occurrence might be told, whereas there is a certain solemnity about the repetition of a folk-tale proper. In most tales and stories leprechauns are depicted as generally harmless creatures who enjoy solitude and live in remote locations, although opinion is divided as to if they ever enjoy the company of other spirits. Although rarely seen in social situations, leprechauns are supposedly very well spoken and, if ever spoken to, could make good conversation. A leprechaun is shown crafting shoes in this Engraving made in 1858. In previous years leprechauns had a less homogenised appearance.Among the most popular of beliefs about leprechauns is that they are extremely wealthy and like to hide their gold in secret locations, which can only be revealed if a person were to actually capture and interrogate a leprechaun for its money. By nature, leprechauns are said to be ill-natured and mischievous, with a mind for cunning. Many tales present the leprechaun as outwitting a human, as in the following examples.

LOL - I think I dated one once ;-)

We'd all be in Lucky Charms up to our ears. ...*shudders*

Then we could have an open Leprechaun hunting season. One of their heads would look good over my fireplace and it would be a good talking point.

then i'd try and find the pot of gold at the end of a rainbow.

then we might be in trouble

What do you mean? They don't?