Someone's leaving the office. He may be switching departments, leaving work to start a family or reaching out for bigger and bolder things. Whatever his reason, it's a nice gesture to put together a farewell lunch to give all your colleagues a chance to toast his future and say their goodbyes. Get things organized by handing out invitations so everyone knows where to be at what time. You've got a lot of options for what you say in your invitations, from classic to humorous to thoughtful. The one you choose depends on the colleague and the circumstances.
Going formal is perfectly appropriate in certain situations. You may be organizing a send-off for a college professor or a well-respected attorney, or you may be in charge of making the invitations for someone you don't know very well. In these cases, choosing a formally-worded, simple invite is fine. Say, "Your presence is cordially invited for the farewell lunch for so-and-so," or "Please join us in a farewell lunch to celebrate the professional accomplishments of so-and-so."
Relax a Little
When you're creating an invitation for someone you know well, especially in a work atmosphere that is friendly and relaxed, you can be much more personal with your wording. "Come join us for food and drinks to celebrate so-and-so's brand-new job!" or "Kim's outta here! Let's all wish her well with a big lunch send-off" are good ideas. Tie in an element of what's going on if you'd like, such as: "We're sad to see Brian go, but let's wish him the best in his new writing career by giving him a great lunch!"
Humor is appropriate for a colleague you all know well and have had great times with, especially if he's a character. Bounce ideas off other colleagues to get the right tone. Incorporating an inside joke may be perfect, or use verse to make it light-hearted and fun. Something like, "Jim is gone; But we're not sad; He's leaving us; To Become a Dad!" strikes the right balance between missing someone and wishing him the best in his future.
While you're printing a dozen or so invitations for the guests, don't forget the star of the show! If it's to be a surprise, innocently ask the guest of honor to join you for lunch and don't take no for an answer. You may prefer to create an invitation specifically for him. Try a formal invitation like, "Your colleagues at Smith Law Firm want to wish you the best in your new endeavors. Please join us at Dressy Cafe for a farewell lunch," or an informal one like, "We're all getting together for a farewell lunch for you and you're not getting out of it! Come on to Relaxed Buffet to gain a few pounds while we wish you well" are good ideas.