How about:

Reading too many posts on the low carb board made my brain fat with information and therfore caused a weight gain (I think, therefore, I'm fat?)

The scales are conspiring against me to threaten my sanity.

The kids/co-workers/DH are playing with the scale to threaten my sanity.

I've already lost my sanity (kids will do that to you, you know).

Air really DOES have calories and so does water!

It's a full moon.
It's a new moon.
I've been mooned (and traumatized severely)

I picked a bad body to be reincarnated into; my past life's Karma is catching up with me and this is my punishment.

Bellybutton lint/toe fuzz will hold 100x it's weight in water.

and last but not least:

I failed to make the required sacrifices to the whoosh fairy!


Too funny, y'all...keep 'em coming! I really needed a good laugh today and this was it!