Doing lunch is a popular way to socialize and enjoy a meal with friends or colleagues. The term 'do lunch' can be broken down into three words: 'LET's, ' 'EAT, ' and 'CATER.' The word 'LET's' is an abbreviation of the phrase 'LET us, ' which is used to suggest an action. The word 'EAT' is a verb that means to consume food. The word 'CATER' is a verb that means to provide food for a special event or occasion. Together, these three words form the phrase 'do lunch, ' which suggests that people should come together to enjoy a meal.