I have a philosophy that has developed over time, which I summarize as, "Everyone on the Internet is a penguin, until proven otherwise."

There are a lot of specific things that are the bedrock for that statement. In no particular order:

1. It is a general reminder to myself that I never really know who is on the other side of a conversation.
2. Imaginging a world full of penguins tapping away at keyboards is something that makes me smile.
3. I initially said, "cats", after seeing the gibberish one particular cat would type into chat sessions when pouncing upon his owner's keyboard.
4. I have met a few people who hate cats, and could not get past them to see my genera point, so I needed a different critter.
5. Using "dog" in place of "penguin" that statement would mean I was calling everyone a dog. Guaranteed to offend some, where no offense was intended.
6. The unicorn folk are scary when provoked. Also, the IPU thing has its own message, and I did not want to mix the two.
7. I have yet to meet someone who loathes penguins. With a population of 6 billion, odds are good that someone does. If you are one such person, I apologize. However, deal with it.
8. Back in college, there was one person who used the nickname, "Green Eyes". Most people assumed that was a nickname for a female. He was actually amused by this.
9. Also back in college, we had someone try a password theft scam against several users. He got caught, and counter-scammed so we could gather proof of his deeds and turn him in to the authorities. They revoked his access. I was one of the victims. Scott Alexander - I remember your name to this day. You were the first person on my, "never hire this dweeb," list.
10. Live and learn. A little paranoia is wise.
11. A lot of paranoia is not.
12. "Skeptical" seems to work for me. No, child of Dr. O'NgMumble, I will not help you try to transfer huge wads of cash out of your country in exchange for my current bank balance.
13. If you always assume that, "too good to be true," must be a reason to flee - then you will occasionally miss out on a real good thing.
14. If you have read this far, it should be obvious that I do not take the statement literally. However, if someone should read those words and decide to follow them literally, they will still be protected. I find that thought comforting, in a way - if my words can be mis-interpreted and still result in good ...
15. Sometimes, you do not need to "prove otherwise". I really don't care if my on-line friend from the other side of the world is a person or a penguin. What matters is the friendship.

If I recall any other subtleties, I may come back and post addenda.