這是一個充滿想像力且令人捧腹大笑的故事。主角機器人伯納德 (Bernard) 某天在公園玩盪秋千時，竟然不小心把自己的「屁股」給盪丟了！於是他踏上了尋找屁股的旅程。搞笑的是，他的屁股一路上被小鳥拿去當鳥巢（但太重了）、被小熊拿去當鼓敲（但聲音太清脆了）、還被松鼠拿去蓋沙堡……到底伯納德最後能不能順利找回他的屁股呢？Bernard the Robot loses his bottom on the park swing, and sets off to find it. Every time he gets close, it disappears again! Bird was using it as a nest, but it was too heavy; Bear used it in his drum kit, but it was too tinny; the Squirrels built sandcastles with it...and now it looks as if they're sailing away in it. Will Bernard EVER get his bottom back?
