The text plays on the common motivational phrase 'If at first you don't succeed, try, try again,' but twists it with an unexpected ending. The humor comes from the literal interpretation of not succeeding at skydiving, implying a fatal outcome, rather than the usual encouragement to persist in the face of failure. It does not rely on different meanings of a word or similar-sounding words.
If at first you don ' t succeed , then skydiving isn ' t for you .