I've been trying to understand lyrics of a j-pop song by Utada Hikaru. It's your typical pop fare, with a healthy dose of unrequited love and self-affirmation. At one point in lyrics, however, the story takes a weird turn:
What is that vaulting horse doing there?! The naive interpretation is that the whole story is happening in a school setting, and it's a literal reference. I'm guessing that 跳び箱 might have been used to mean an obstacle/hurdle to overcome - together with subsequent practical advice on how to vault it. I just haven't met any idiom like this before. Is it an actual phrase/idiom, or just licentia poetica? :)
Full lyrics are here if you need more context.