Karen's Big Joke is the twenty-seventh book in the Baby-Sitters Little Sister series.
Back Cover SummaryEdit
Karen loves April Fools' Day. That is when she gets to play tricks on her friends. First she squirts Pamela with a fake camera. Then she puts a plastic cockroach in Bobby's shoe.
But now Karen has come up with a joke to play on her whole big-house family. Could this be her best joke ever? Or is Karen in for a big surprise?