Here's why:
* "Stump" usually refers to a tree trunk without branches, or a difficult problem.
* "Rabbit" refers to the animal.
It's possible you're thinking of:
* "Rabbit hole": This is a metaphor for a situation that leads to increasingly complex or confusing situations.
* "Stumped": This means to be confused or unable to solve a problem.
If you can provide more context, I might be able to understand what you're asking!