There was a custom of holding meetings before, which was a way of private fund-raising and was more common in the Republic of China.

Have a meeting, for example, five people raise money for the first person, and the first person can only take out the money next time, but can't use it, and so on. After five fund-raising, that is, everyone used up all the money, the meeting was dismissed.

Black signing means I'm going to make a black signing, and I'll use this money first. In the future, I will only take out the money and will not use it again.

There is such a description in Mr. Lao She's Camel Xiangzi.