Proof that Christmas is actually Halloween.

Being the übernerd that I am, I found the following proof which I saw on a board at work humorous. The crux of the proof is that 25 in decimal numerals is equal to 31 in octal numerals (see the Wikipedia article on octals if you don't understand this). Since DEC(25) = OCT(31), one could argue that December 25 is October 31. Therefore, Christmas is Halloween.