India and South Africa faced off on May 15, 1999 in the World Cup. The latter would win the game but a cloud of controversy would be cast upon the match.
AFP
What exactly happened? Well, Hansie Cronje was communicating with coach Bob Woolmer for the entire duration of the match. Yes, you got that right! How was he doing it? Simple, the skipper used an earpiece to talk to Woolmer while fielding and they discussed their strategies.
When they were hauled up for this, both maintained that they had done no wrong as there is not a law to bar them from doing so. They were right because at that time no rule mentioned earpieces could not be used.
Reuters
However, the spirit of the game came into question and eventually the ICC decided to ban the use of such devices for the rest of the tournament. But the damage was done due to this joint venture by both captain and coach.