"Shirley Shells Out" is the twentieth episode of Viva Piñata's second season, and the seventy-second episode of the series overall.
Shirley Shellybean participates in a race, despite being the slowest piñata on Piñata Island. She is given a sour potion by Professor Pester which transforms her into a Sour Shellybean. Turning into a Sour Shellybean makes her go supremely fast to the point that she manages to break the sound barrier. However, the potion wears off before breaking the finish line and she ends up giving up on winning the race due to how much damage she caused while sour. Pecky Pudgeon wins the race accidentally due to breaking the finish line.