In speaking with this major prick of the Strogg and telling him about Earth, you acquire a signal to Earth's television broadcasts.  You flick through the channels, but he keeps stopping you at a football game.  He was very impressed how one team just marched up and down the field, totally decimating the other team.  He comments on how fun the game could be with weapons.  They were probably watching the Eagles (I'm from Philly).  A deal is made and a date is set, the battle over planet Earth will occurr on a football field.  Team Marine vs. Team Strogg.