Snowball effect - This idiom describes a situation where something starts small but quickly grows larger, gaining momentum like a snowball rolling down a hill. It can refer to both positive and negative situations. For example: • A small investment turns into a fortune. Someone starts with a little money, reinvests wisely, and eventually builds great wealth—a snowball effect of financial success. • A tiny mistake spirals into disaster. A minor error in a report leads to confusion, missed deadlin