The next day you go to the old oak and find the ring of shamrock. You step inside and wait.
After a few minutes you hear an Irish-accented voice. "Have ye decided to apply?"
You look down and see a small person with a tricorn hat green and red jacket. "Er..yes." you reply, bending down "I've come for the leprechaun job."
"Excellent!" says the Leprechaun "My name's Cornieous O' Taraugh and I'll be your supervisor and trainer. You can call me Cornie. Are you prepared to be brought down to size? Our factilities aren't built for a big fella like you."
After a moment's thought you agree. "Very well."
"That's the spirit!" re replies and sprinkles some dust over you. You start to shrink inside your clothes, which fall as a pile. and emerge the same size as Cornie, dressed in only your vest and undies.
"Now, let's be on our way." says Cornie
"What about my clothes?" you ask.
"Ye'll be getting new ones for working, and I'll sent some other folk up for your human clothes." says Cornie "Now, let's go to the fairy world.". You follow him to a hole in the roots of the oak tree and down a tunnel.