I normally have the same response when I hear a Guns N Roses tune!

Being a musician, I had to look up Mattie Groves. The midi file can be heard at: http://www.contemplator.com/child/mattie.html

It take about 15 seconds per verse, so that would be 30 seconds total. A much easier song (since I'm sure most people, including myself can't hum Mattie Groves) is Row, Row, Row Your Boat which takes about 7-8 seconds per verse. It was suggested to me by an RN, so I know it will work!

Now let's see---that makes 4 verses to reach about 30 seconds....and you'll have the added benefit of having RRRYB going through your head the rest of the day!