The key point of xiang sheng is nourishing "the bundle." This so-called "bundle" is the punch-line. When performing, the actors wrap up the funny statement, then through various techniques, they unveil it, bringing the audience surprising feelings that make sense in the context. This is called "shaking open the bundle."
講相聲的關鍵在於照管好「包袱」這玩意兒，所謂「包袱」就是把大家逗樂的地方，表演時先把可笑的東西包裝起來，再透過種種手法把它一層層打開，帶給觀眾出乎意料，卻入乎合理的感受，稱之為「抖包袱」。