Shelby Joy is a girl seen in the series as a background character. Her name is revealed on What's Your Favorite Word? which she was on when she was 10 years old. Her favorite word at the time was "exquisite".
Another 10-year-old girl named Kabrina, who is identical in appearance to Shelby Joy, appeared in a different Favorite Word episode. This may have been due to an editing error.
Interview for WYFW
My favorite word is "exquisite". This is because I like the way it sounds in my mouth. Starting in second grade, my grandma was always saying to me, "You look very exquisite today." So that's how I began to like the word.
She is also seen outside the school later in the episode listening to Tobey's speech, standing to Steven's right and Ben's left. The unnamed blonde boy she walked past in the hall is also on Ben's right.
In Robo-Camping she is seen at the start with a man who is probably her father, since parents are dropping their kids off at camp. Her father resembles the Mayor, but has a slightly bigger nose.