Where I live, the entire population does not stop working and just stare at the wall until it's time for the next game.
Summer in general may have an effect on sales, although June/July have been quite good for me lately, but the World Cup? That's using your imagination a bit too much I think.

If you have football/soccer related assets, you might just see an increase in sales. I just sold a clip like that yesterday (I only have one).