I’m writing on this topic as I recently attended a cup game in which a team was losing by one goal in the last minute and having won a corner, the coach told the goalkeeper to go up only for the young player not to know what the coach meant.
It was quite possible that the goalkeeper was not aware that in a last ditch effort to get an equalizing goal, the coach was risking having the goal open and asking the keeper to get into the oppositions penalty box to possibly become a hero!
The video below shows some examples of goalkeepers going up for corners and scoring. By going into the opposition’s penalty box the goalkeeper attracts attention and can even be used as a decoy for other forwards to sneak in and score unopposed.