Do you know anagrams? This GNU page features some pretty funny ones. I like these two best :):

Original: PRESIDENT CLINTON OF THE USA
Anagram: TO COPULATE HE FINDS INTERNS

And of course:

Original: “That’s one small step for a man, one giant leap for mankind.” -Neil Armstrong
The Anagram: “A thin man ran; makes a large stride, left planet, pins flag on moon! On to Mars!“