Reaching the moon!
Consider a standard A4 paper, with ~0.1mm thickness. What is the smallest number of times you will need to fold that paper so that its thickness is at least equal to the distance between the earth and the moon?
You may take the distance earth-moon to be approximately 384,000km.
Hint : it is less than 100, because, at 100 folds, your paper will stretch well over our galaxy!