What are some funny jokes that you can't think of ending?

A billionaire is dying, and his three sons are fighting fiercely for their inheritance. Before he died, he gave each of his three sons 100 yuan, and told them that whoever could buy one thing to fill the whole house with the least money would inherit all the property. So the three sons went out thoughtfully. The eldest son came back first. He spent 100 yuan on a car full of cotton. He dragged fluffy cotton into the room with difficulty, but cotton only occupied half of the room. The rich man shook his head in disappointment and told him to step aside first. Followed by the second son, who spent 100 yuan on a gas tank. He confidently carried the gas tank into the room and turned on the switch. The smell of gas filled the whole room instantly. The rich man smiled with relief, indicating that he could turn off the switch and open the window for ventilation. Then the third son rushed in with a lighted candle in his hand and shouted excitedly, "Haha, I only spent ..."