Spaghetti Cat is a picture of a cat eating spaghetti (duh) that was first featured in the "Morning Show with Mike and Juliet".
It appeared as a random image which interrupted a lady in mid-sentence discussing 'women and binge drinking'
It has also been discussed on The Soup and various other websites.
The only explanation given was that it was a "bleep photo"...and there's "more of those in the future." Brilliant.
Ultimately, no one knows of it's true origins. (yet)