If my increasingly faulty memory serves me at all, this song was the theme song from a mid-70's movie about Muhammed Ali ("The Greatest" perhaps?).

In addition to George & Whitney, there is also an hysteric 50's-rock styled version by a band called Big Daddy on their cd "Cutting Their Own Groove" on Rhino (R2 70733). Definitely off the beaten path, but perhaps that's how the cat got muddy in the first place.