Astronomers. They are a pretty friendly bunch. They like nothing more than to share the wonders of the universe and the beauty of the night sky with others. Whether it's someone who studies astronomy for a living or someone who indulges as a hobby, they are usually a pretty amiable lot.
But if you want to see them get perturbed and a bit red in the face, there are a few sure-fire ways. Certainly if you asked each individual, they could probably come up with more than five, but these five seem to be universal. And now, in reverse order:
Number 5: Use lights at a star party. Arrive after it's completely dark. Pull your car up to the group with their telescopes all set up and shine your bright headlights right into their faces until you can actually see their pupils lose dilation. After you get out of your car, walk onto the field with your deer-spotting hand lamp and shine it around until you find a good place to stand. Then when you are all set up and don't need your lights anymore to see the way, shoot off some fireworks to entertain those poor, bored astronomers.
Number 4: Buy a star. Contact one of the many "star registries" to purchase the pretend naming rights to a random star in the sky that is too faint to see. Then try to find your name on any official star map to show your astronomy friends. Or better yet, send me your fifty bucks and I will print out my own star chart with the printed designation of one star photo-shopped out and your name there instead. Polaris? Not any more. Now it's the Jimbo Star.
Number 3: Claim the moon landing was faked. This one is really about the "debunker" and his or her discomfort with the advancement of science and technology. Which probably means they are not all that fond of people who can "see back in time" or those who "discern the beginning of the universe." Any easy way to slip in this pet peeve is anytime someone says, "If they can put a man on the moon...." interrupt them and say, "That never really happened." This might also get you a job at Fox Television.
Number 2: Talk about aliens and UFOs. Discuss the strange lights you have seen in the sky: the blinking noisy craft that move overhead, the non-blinking tiny lights that soar smoothly from horizon to horizon, and the waving and shimmering bands of light you sometimes see invading the north. Ask to look through their telescope so you can find evidence of little green men on Mars. See if they'd like to hop the fence with you at Area 51 and "check things out."
And Number 1: Confuse astrology and astronomy. Enough said.