Appropriate messages for a retirement card include telling the retiree that he should not work any longer because he won't get paid for it. Depending on the circumstances and personality of the person retiring, appropriate messages may be sincere or funny.
In a funny retirement message, the writer can express condolences to the retiring person's boss on the devastating loss he now faces. A simpler funny retirement message involves telling the person that being retired does not mean that he aisre expired. One funny message analyzes the word itself to tell the retiree that the word "retired" makes it seem as if he should be getting tired for the second time.
A sincere retirement message can express admiration of the retiring person's long career, saying the retiree should enjoy his retirement because he has worked so hard for it. Another sincere yet funny message tells the retiree that he is likely to be busier than ever even though he is retired because there is no rest for the wicked. A simple and sincere retirement message involves telling the retiree that he did many important things at work and he is likely to continue to do many important things now that he is retired.