If you've got extra skin hanging out  between the end of the nail and the tip of the finger, you've got a nasty and explosive temper. Watch out!

Nails with a reddish hue also indicate that you got a hot-temper.

Another way to tell is by your thumb. A bulbous thumb, the old-fashioned "murderer's thumb," shows a strongly physical approach to life with strong appetites. This expression, "resistance is futile" is very apt here, and people with bulbous thumbs have quite heated tempers.