Complex sentence: Ed and Eddy's subsequent prank leads Edd into believing that Eddy and Ed have sunk to their demises in quicksand, he mourns before they reveal that its a trick, and Eddy makes fun of Edd for his sentiment.
Split into simpler sentences: Ed and Eddy's subsequent prank leads Edd into believing that Eddy and Ed have sunk to their demises in quicksand. He mourns before they reveal that its a trick, and Eddy makes fun of Edd for his sentiment.