American shoppers usually do not like it when a store is so cramped that the customers may touch one another while shopping. When the Butt Brush Effect occurs, customers decide to leave without making a purchase.
In days of big sales, stores are most likely to be occupied by large number of people and people may be pushed by other people, or table, or any piece of merchandise from the back. People, especially ladies do not like it at all. So they prefer to leave the shop instead of continuing shopping. This effect is called as the Butt Brush Effect.