Well, I guess I know a quick out for any Sci-Fi game... antimatter aliens.
Humans "Greetings from earth, we have a custom of grasping appendages as a sign of friendship."
Aliens "We too hold this custom. Allow us to partake in such a cultural exchange in peace."
People on both sides "Dude! They just blew up or diplomats! Oh, no they didn't, let's kill 'em all!"
Humans "Greetings from earth, we have a custom of grasping appendages as a sign of friendship."
Aliens "We too hold this custom. Allow us to partake in such a cultural exchange in peace."
*Kaboom!!!!*
People on both sides "Dude! They just blew up or diplomats! Oh, no they didn't, let's kill 'em all!"