We had a rather big passenger on board last week who gave my cabin crew grief that our seats were too narrow. Given all 737 are six abreast in economy and there is a standard aisle width I was a bit nonplussed by this. I suggested that if he kept complaining they advise him to buy two seats next time. Definite contender for passenger of the month....awarded to whoever behaves worst on one of my flights....smoking in the toilet/offloaded for being drunk when boarding/standing up during takeoff run etc.