"Excuse me, do you have a pen?"
     "No, but I have a wishbone."
     "How would a wishbone possibly help me?"
     "Depends on what you were wanting to accomplish with a pen. If you were angry and just looking for an object to break in half, then a wishbone would more than adequately fulfill your needs."
     "But I don't want to break anything. I want to write. I thought that would be obvious."
     "Well, the wishbone could still help. You could take it and a glass of water and go outside, dump the water on the ground, dip the wishbone into the resulting mud, and use that to write with."
     "That's too much of a hassle. Besides, I'm filling out an application. I can't turn in an application caked with mud."
     "Well, at the very least you could still use this wishbone to break and provide you a slight aid to your frustration of not having a pen!"
     "No thanks."
     "Last resort: you could try breaking the wishbone and using its power to request a pen."
     "I don't believe in that stuff, but I suppose it couldn't hurt." He accepts the wishbone.
     Just before breaking the wishbone, it occurs to him that perhaps he would be wasting the supposed power of this wishbone by wishing for something as petty as a pen. Perhaps instead he should be wishing for the job itself, or for lots of money so he doesn't even need a job.
     But maybe that's why wishbone wishes never come true. Maybe there was an upper limit to what could be wished for, and people were always too greedy and wished for more than was allowed. So he wishes for the pen and breaks the wishbone.
     In the meantime, the wishbone donor was reaching into his pockets for his cellphone, and exclaims, "Dear me! It appears I had a pen after all! Well how about that!" He gives the pen to the man.
     Amazed and elated, the man accepts the pen, and praises himself for having figured out the secret of wishbone wishing. He eagerly runs back to his application to finish it before the impending deadline.
     And finds, much to his dismay, that he wasted his wish on a pen that was out of ink.