Paradoxes (Thanks to Wikipedia!)
"If this sentence is true, then Santa Claus exists."
Without necessarily believing that Santa Claus exists, or that the sentence is true, it seems we should agree that if the sentence is true, then Santa Claus exists. But then this means the sentence is true. So Santa Claus does exist. Furthermore we could substitute any claim at all for "Santa Claus exists". This is Curry's paradox.

Exception paradox: if every rule has an exception, then there must be an exception to the rule that every rule has an exception.
Variation: The only rule is that there are no rules.

"Practice moderation in all things. Including moderation."

 "Is the answer to this question no?"
 
 

"A Sound of Thunder"
by Ray Bradbury.
"I don't try to describe the future. I try to prevent it."
"Go to the edge of the cliff and jump off. Build your wings on the way down."