Leave this "accident" on the carpet or couch this April Fools' Day and listen to everyone exclaim, "Not me!" for a bit before letting your clan in on the secret: dried paint and glue make a believable mess. This project needs to be made several days in advance, but the payoff is well worth it!
Cut a 2 1/2-inch-diameter Styrofoam ball in half, then shape it to resemble a partially melted scoop of ice cream, smoothing and compressing the surface for a realistic texture. Carve a piece from the bottom of the ball so it will fit snugly over the lip of an ice-cream cone.
Mix 2 tablespoons of tacky glue (we used Aleene's Original) with about 1 tablespoon of pink acrylic paint (keeping in mind that the shade will darken as the glue dries). Drizzle some of the mixture into the cone, then arrange the cone and the ball on a cookie sheet covered with plastic wrap. Drizzle the remaining mixture over and around the ball, then add sprinkles, if you like.
Allow the mess to dry for about 3 days, then remove it from the plastic wrap and let it air-dry completely on a protected surface.