Every year about this time, I tell my kindergarteners and first graders this story...
Once upon a time, I was walking through the woods at night. Suddenly I heard a noise, "Tap-tap-tap...tap-tap-tap..." I quietly crept forward and saw -- a leprechaun! Slowly and silently I snuck up behind him and grabbed him by his coat tails. "Let me go! Let me go!" he shouted.
Now, everyone knows that leprechauns make shoes for the elves and fairies and other magical creatures. And for every pair of shoes they are paid one piece of gold. And if you catch a leprechaun by the coat tails and don't take your eyes off him for a second, he has to give you some of his treasure. (Now, be careful if you do catch one. They are very sneaky, and if you glance a way for even a second they can disappear. That's how their magic works.)
There was no way I was letting the leprechaun go. "Not until you give me some of your treasure!" I demanded. He knew I had him. "Okay, Mr. Mortal Man," he replied, "I'll give you some of my treasure. Ye can have gold -- silver -- or magic crayons!"
I chose the magic crayons. And every year at this time I share them with my students. We all draw leprechauns, and color them with magic crayons. Then we paint over them with water, and the crayon on the paper turns into paint.
The drawing above is one I did using magic crayons. If you'd like to try this, you can catch a leprechaun, or, to achieve a similar effect you can order crayons like these. They are similar, but not quite as magical as those obtained from a leprechaun.