Once upon a time, there was a king who had a daughter of marriageable age. As he was very fond of his daughter and he didn't want her to leave him, he made an impossible offer to his kingdom's men. He announced that whoever has two pricks would be eligible to marry his daughter. The invitation spread
far and wide. Of course there were no one who came forth, and the king was secretly pleased.
In another part of the kingdom, there were 2 woodcutter brothers, Jack & Jim. One day, they chanced upon a very big tree and decided to chop it down for it would fetch them a decent amount of money if sold as firewood.
As they were about to chop it down with their sharp axes, a voice cried out, "STOP! Please don't hurt me ! " The brothers were scared shitless when suddenly an apparition appeared from out of the tree. He told them that he was the genie of the tree and if they would to spare him, he would grant them a wish each.
Remembering the king's offer of his daughter as bride, the brothers each wished for a second prick. The genie said "Your wish is granted. Now... what you have wished for will fall down from the sky. You must catch it promptly with your hands and attach it to where you want it to be !" 
Jack was the first one to receive his wish. As the prick was falling down from the sky, he swiftly caught it with his hands and attached it right next to where his own prick is. 
Now, Jim was the clumsy one. As his second prick was hurling down , he missed and it landed right on his
forehead !!!
Jack, being the cool one, told Jim that it was alright and they should proceed to the palace to seek the princess's hand in marriage. After all, the king did say 2 pricks. Jim, not wanting to expose what he had on his forehead, took a long piece of cloth and wound it round his head like a turban to hide it.
It was 2 days later when they reached the palace. The king was summoned and he asked Jack to show him his 2 pricks. Jack took off his pants and proudly showed it off to him. The king sighed in dismay and resignation and also called on Jim to show him his 2 pricks. 
Embarrassed, Jim took off his pants and unwound his turban to reveal what's on his forehead. The king then yelled in disgust, "NI NA B EH ! YOU THIS TYPE OF LAN CHEOW BIN WANT TO MARRY MY DAUGHTER AH ???!!!???? "
And so the term "Lan Cheow Bin" was coined.