Playing Raffi brings me joy, even when there aren't kids around.  I got these chords 
from watching a video on youtube of him performing (http://www.youtube.com/watch?v=8U3UDl0bUHA)

Each verse goes like this:
Dm                        A          Dm
You gotta sing when the spirit says sing
Dm                                   A
You gotta sing when the spirit says sing
Dm                                    Gm7
When the spirit says sing, you gotta sing right along
Dm              A          Dm
Sing when the spirit says sing

Then repeat for each verse:
You gotta clap...
You gotta hum...
You gotta snap...
You gotta swim...
You gotta stomp...
You gotta hush...
You gotta sing...

The ending goes like this:
Dm                        A          Dm
You gotta sing when the spirit says sing
Gm7                       A          Dm
You gotta sing when the spirit says sing
Gm7                       A          Dm
You gotta sing when the spirit says sing
Dm                            A          Dm
And you gotta stop when the spirit says stop

For the two outro chords, play the top 3 strings (GBE) at the 7th and then 8th frets.

Note: the Gm7 is played as 353333

Enjoy!