Well, you can fill out a request slip and say "Person's Name is having a (anniversary/birthday/retirement/new job/etc). Please bring them up and embarass them!"
******* DISCLAIMER ******** Doing so starts a series of events resulting with The Guys bringing sed person up at some point throughout the show, announce the stated milestone, and most likely results with them being sung to. (More often than not, a song designed to make this person uncomfortable - soliciting a rousing response from the rest of the audience)...
******* DISCLAIMER TO DISCLAIMER ******** A huge sense of humor of the temporary on-stage guest is required. This is not for the thin skinned!