How about the sun? You can see it and feel its heat, but I'm fairly positive that it will kill you if you get too close.

Here's another one: A man was to be sentenced, and the judge told him, "You may make a statement. If it is true, I'll sentence you to four years in prison. If it is false, I'll sentence you to six years in prison." After the man made his statement, the judge decided to let him go free. What did the man say?