pipe-opener

noun5

1. •
   A device or mechanism for clearing obstructions in a pipe.
2. •
   A practice event; a warm-up.
3. •
   (figurative) A brisk walk or other aerobic exercise; a constitutional.
4. •
   (figurative) An example that serves as an introduction.

   • That tale may have served as a pipe-opener, but one could not see its wood for its trees, so I threw it away. — 1991
5. •
   A device for putting a hole in a pipe.