Ok, so this is the one you've all been waiting for...
An ancient temple is found underground PETA headquarters. They send a team to investigate this temple, and decide it'd be the perfect place to hold one of their hippy pinko commie parties. So, they hold it there, in a room with 12 raised "Table" like objects.
They find some guns in there. They touch them and the entrances seal. Suddenly, three Predators appear...