Of course, there is a whole theory underlying this idea. "If a tree is chopped with three or four strokes but does not fall [if someone is given the sales pitch three or four times but still refuses to join], then that is one strong tree.
這背後又有一套奇怪的理論：「一棵樹如果被砍了三、四刀還不倒（被推銷了三次還不加入），那他真是一棵大樹。