Too bad there's no way to send out a signal to any spaceships entering Earth's atmosphere advising them of basic social etiquette.

Maybe something like:

[And here, she switches to a tone that sounds much like a flight attendant.]

"Welcome to Earth. We hope you enjoy your stay, but first, there are a few simple rules to observe. First, do not try to blow the planet up. Second, do not try to take over. Failure to follow these rules will result in a curb stomping from Earth's heroes. Thank you, and have a pleasant visit."