original version (here's the original audio recording of the commerical):

Who walks the stairs without a care?
It shoots so high in the sky.
Bounce up and down just like a clown.
Everyone knows it's a Slinky.

The best present yet to give or get.
The kids will all want to try.
The hit of the day when you are ready to play.
Everyone knows it's a Slinky.

It's Slinky, it's Slinky.
For fun the best of toys.
It's Slinky, it's Slinky.
The favorite of girls and boys.

alternative verse (newer version):

What walks down stairs, alone or in pairs,
And makes a slinkity sound?
A spring, a spring, a marvelous thing.
Everyone knows it's a Slinky.

Here are some video clips of classic Slinky TV commercials:

• from 1960's
• from 1970's
• from 1980's

Here's a video of a slinky going down stairs, with super-slow-motion video from a high-speed camera:

• Slinky stair-descending video with super-slow motion