1. No one but their creator understands their internal logic.

2. Even the smallest mistakes are committed to memory.

3. The native language used to communicate with others of their kind is incomprehensible to anyone else.

4. The message "bad command or file name" is about as informative as "If you don't know what's wrong, then I'm not going to tell you."

5. As soon as you make a commitment to one, you find yourself spending half your paycheck on accessories for it.