Ah begorah, per Wikipedia, a leprechaun (Irish: leipreachán) is a type of male faerie said to inhabit the island of Ireland. Some say the name leprechaun is derived from the old Irish word "luchorpan" which means "little body."
Leprechauns are faerie cobblers who make shoes for elves. They are always aged and diminutive men (2-3 feet tall) sporting bright red hair and beards. They wear emerald-green frocks and tall top hats. The green is to help them blend into the countryside and disappear from view. Their great wealth and greed is legendary (i.e. they have pots of gold which they hide). They're usually reclusive. Some people think they're mean. They're also pranksters.
According to myth, leprechauns have magical powers such as hypnotism, trickery, and control over the intricate workings of Earth and metals such as gold and silver. They regard humans as foolish and greedy and so avoid contact. If a human sees him, he will vanish as soon as the human takes his gaze off him. However, they can be generous to humans who do a good turn for their benefit.
If a leprechaun ‘adopts’ a family things go missing, or appear in unexpected places. Furniture may be moved around the room, and the whiskey or milk will disappear overnight. If this should happen to you, you must start leaving presents of food, drink, and anything else to keep the lhim happy. With any luck, the leprechaun will go round the house and barns at night finishing off jobs that the big people have had no time to do (and not cause his normal mischief.
Legend also reports leprechauns will drown in a light rain, float away in a breezy day and can get buried in a snowstorm.
To catch a leprechaun means to possess his treasure. However, be warned, he's a very hard creature to find, much less hold. Remember, you can't take your eyes off him for even an instant, lest he vanish.