Why are World Cup refs giving red cards to players covering their mouths when confronting opponents?

World Cup players were warned before the tournament about a new rule that would result in an immediate red card for anyone covering their mouth when verbally confronting another player. Officials are actively enforcing that rule change. The latest incident came on Tuesday night when Ecuador defender Piero Hincapié was sent off in second-half stoppage time of his team's 2-0 loss to Mexico in the round of 32.