Lord's, England v West Indies, 2004, Day Four.
A family sit down in front of myself and my mate at the beginning of play, and after a while we begin chatting to them. The father is West Indian, the mother English, and the two young boys (aged about seven and nine) are both wearing West Indies caps. Just after the lunch break they leave their seats to get some food, hoping to have avoided the lunch-break rush.
Shortly afterwards, two Australian guys in their twenties arrive and sit exactly where the family had been, in the front row right by the boundary, the row in front of me and my mate. They remain there for a while, until the family return with food about 20 minutes later.
The family ask the Australians politely if they would mind vacating their seats - they refuse, and nonchalantly flash a pair of MCC members' cards at the family. They claim their status as members means they can sit wherever they like, whenever they like. Obviously the family disagree, and so does everyone around them - the Australians have done nothing but viciously sledge Matthew Hoggard and Robert Key (fielding nearby) since they took their seats.
Someone behind us pipes up "someone's sitting there, mate" to the Aussies - soon enough there are at least 200 people in the surrounding area kindly pointing it out, and before long everyone's laughing at the Aussies' annoyance. The family go and get a steward, who argues with the Australians unsuccessfully for a few minutes, before the father of the family gets fed up and decides to take manners into his own hands.
The father moves from his position in the gangway, and plants his six-foot-five frame directly in front of the Australians, blocking their view of the game. There's a huge cheer from the surrounding crowd, and eventually the two guys decide to move, after much complaining, and amid a chorus of goodbyes from a good few hundred people. It was classic.