In my chapter alums were always welcome, but there were a couple of alumni who wore out their welcome by basically causing problems and telling the undergrads that "you can't do anything to me cause I'm alumni". Our alumni association took action against them.
Also a couple of years ago I was at Homecoming, and this girl (think DrunkGirl from SNL) walks in the party and exclaims really loud "Why are there so many OLD people here???" (bear in mind most of us were in our 30s).
