Why do people rub their thumb and finger together?

Counting money. Rubbing the thumb and finger together is a common gesture for counting money. This gesture is thought to have originated from the ancient practice of weighing coins on a scale. When a coin was placed on the scale, the person would rub their thumb and finger together to increase the friction and make it easier to weigh the coin. Over time, this gesture became associated with counting money in general, even when no scale was involved.

Expressing satisfaction or approval. Rubbing the thumb and finger together can also be a gesture of satisfaction or approval. This gesture is often used when someone is pleased with the way something has turned out, or when they want to express their appreciation for something.

Indicating secrecy or conspiracy. Rubbing the thumb and finger together can also be a gesture of secrecy or conspiracy. This gesture is often used when someone is sharing a secret or making a plan with someone else.

Asking for money. In some cultures, rubbing the thumb and finger together can be a gesture for asking for money. This gesture is often used when someone is asking for a loan, or when they want someone to pay for something.