* "Welcome to Earth" (after I punched it, a la Independence Day)
* "What is that bad smell?" (something my son usually says when he smells something alien cooking in the kitchen)
* "Do you get cable on that spaceship?"
* "What's your Internet speed on your home planet?"
* "What is the airspeed velocity of an unladen swallow?"
Any other suggestions? What would you say if an alien arrived on the planet and you were the first person it wanted to talk to?