Once recently I was upstairs on a four seven-400 and a "gentleman" was getting snippy about channel 9 being activated. As most or you know it's differant on -400's (I think 13?). In any event the FA intercom somehow got pumped into the entertainment system and a few of us were truly entertained by the insights provided by the FA's conversation regarding this guy. Before she went too far I motioned to her and let her know she was broadcasting to the pax. Her expression was priceless!! Both she and the purser were very appreciative of the heads up.