I'd never heard it before my kids just started singing it. In southern Massachusetts, they sing it like this:

Croc a dilly oh mi quak quak quak
Say sinco sinco, sinco sinco sak
Follow, Follow
Stick your head in Je-llo
Dye your hair ye-llow
Eat a marshme-llo
1,2,3,4,5,6,7,8,9,10!