VIDEOS:
Go Get It!
An in-universe example in "Ruff Fetches the Fetchers" where the theme song of a rival cat-themed rip-off of FETCH! called Go Get It! sounds exactly the same as the theme song of Ruff's own show.
Example of:
Suspiciously Similar Song
FETCH! with Ruff Ruffman
Example of:
Expository Theme Tune