Why don’t aliens pop in for a chat?

If there are UFOs, why don’t they come down and say hello?

Here’s some good reasons :

- the military will capture/kill/disect them

- we eat meat, maybe we might eat them

- humans are unpredictable and can kill at any time.  It’s plain dangerous for aliens here

- we’re about a billion years behind them evolutionary-wise

- bacteria on this planet might kill the alien species as their immune system is setup for a different planet

- Jerry Springer put a lot of them off the idea of visiting in person