Here is a good one - apparently it happened in a local league in the UK ( I'll spare blushes by not naming names lol ). If true, it's a cracker, if it's made up, it's still a good story.
Non-playing team captain is with his team in the playing venue. One of his players hasn't arrived yet. The clocks are started and the captian leaves the venue to make a mobile phone call ( obviously this is fine, he isn't playing ) to the missing player to see where they are. Unfortunately for them, the missing player has entered the venue via another entrance and has taken his place at the board. His phone rings ( it's the team captain calling!!! ) and he has to forfeit.