The person who falls for the joke is the fool, the april fool. You have to say april fools like that to show that you're joking. Some famous april fool jokes include ones done by the b b c. They broadcasted a report about how spaghetti was actually harvested from trees in switzerland. And ye, it showed people climbing up ladders to pick the spaghetti and collecting it in baskets. Many british people in 19 57 were completely fooled by this.