I was on a buddy pass one time and was seated on the plane chatting to other passengers when I heard my name over the PA. (this was Southwest, so no seat assignments). They took me off the plane to give my seat to a revenue passenger. I think they had different levels of passes--Some you could book in advance and some, like the one I was on--were last minute and at more risk for cancellation. My buddy was also my boyfriend and was a 1st officer so I would try to travel with him if he was flying some place interesting. However, if there was some place that we HAD to be, I would buy a revenue ticket and not risk getting bumped. He received a limited number (maybe 2?) per six month period (I think). At the time (pre 9-11) they would also give the employees buddy passes for things like perfect attendance!