Living well is the best revenge. The second best revenge is carefully removing plants from someone's garden & replacing their lawn gnomes with slightly larger lawn gnomes so they appear to be growing in size from eating the plants.
@roxiqt We did a variation of this at work. Progressively replacing a supervisor's dust coat with a slightly smaller version, and moving things in his corner of the bull-pen so the access to his desk and the space behind his desk was getting smaller and smaller. All it took was a few people commenting that it looked like he was putting on weight ...