A friend posed the following word puzzle to me:
Can you think of a sentence that keeps the same meaning whether you use "it's" or "its"?
He asserted that this puzzle does in fact have a solution. However, it has me completely stumped. I tried to solve an easier problem, to find a sentence which is still grammatical if you change an "its" to "it's", but all I could come up with is examples like "It's light!" (which is, strictly, more of a sentence fragment).
What is the solution to the word puzzle? Or, is there some way I can "prove" that the puzzle should have no solution?