Let's get together to meet and have lunch sometime in the future. A clichéd, noncommittal expression often associated with upper class people. A: "I'd love to sit down with you sometime and go over some ideas I have for the business." B: "Sure thing, kid. Let's do lunch—call my assistant to arrange a time." I really must run, darling, but I'd love to catch up with you soon. Let's do lunch sometime!