The full story:
"VERY early in the production of Steven Universe, we had to do storyboard pitches to the higher-ups at Cartoon Network. Basically, these are very important meetings attended by the executives so they can check in on the tone of the show and storytelling and give us notes on how to proceed.

We were preparing the pitch of Serious Steven when i noticed the date: April 1, 2013! We couldn’t just let this opportunity slip through our fingers! I very quickly whipped together this board in the half-hour before the pitch. I showed it to Rebecca and she thought it was crazy but agreed to pitch it in the meeting right before we pitched Serious Steven.

Rebecca introduced this board in full seriousness and then did a full pitch, including all of the character voices. First it confused everyone, but then the whole room got into it. Uncle Grandpa and Clarence are kind of the “sister” shows to SU because they were developed and greenlit around the same time. Eddy got the biggest laugh. I included him because Ed Edd n Eddy was one of Rebecca’s biggest inspirations and we have a former EE&E storyboarder (Raven M. Molisee) on staff.

A good thing that came out of this board was that it pushed Pearl’s potential as a comedy straightman to the limit(At the time, anyway. We’ve definitely gone way further at this point). When Rebecca later pitched the idea of “Say Uncle”, we recalled this board when thinking of the chemistry Pearl might have with an interloper from another universe." -Ian JQ