TV theme songs, once a vibrant piece of pop culture, have been on the wane for years as networks experimented with ways to keep viewers from switching channels. Their mission?

Then there are the songs that take familiar melodies and attach really stupid lyrics to them. Like the “Barney Theme Song,” which corrupts “Yankee Doodle” into a purple-dinosaur ...

NPR marks the 25th anniversary of a bouncing, purple T-Rex with oddly regular teeth, and a theme song that delighted toddlers, but to this day puts thousands of parents on edge.