I'm sure that the song is played in E:

so the chords are E to A to B to E all the song repeated.

E chord:

E | -------- | 
B | -------- | 
G | --1----- | 
D | --2----- | 
A | --2----- | 
E | -------- | 

A chord:

E | -------- | 
B | --2----- | 
G | --2----- | 
D | --2----- | 
A | -------- | 
E | -------- | 

B chord:

E | --2----- | 
B | --4----- | 
G | --4----- | 
D | --4----- | 
A | --2----- | 
E | -------- | 

to make it more interesting (chuck does so) play this at the beginning:

E | --------------------------------- | 
B | -----0-----0-----0--------------- | 
G | -----1-----1-----1--------------- | 
D | --2-----------2------------1--1-- | 
A | --------2------------2--4-------- | 
E | --------------------------------- | 

when the text comes in play this:
   
   E           A               B                    E
E | ------------------------------------------------------------------ | 
B | -----0-----0-----2-----2-----4-----4-----4-----4-----0-----0------ | 
G | -----1-----1-----2-----2-----4-----4-----4-----4-----1-----1------ | 
D | --2-----------2-----------------4-----------4-----2--------------- | 
A | --------2-----------0-----2-----------2-----------------2--------- | 
E | ------------------------------------------------------------------ | 
    When I was  a little biddy boy, my grandmother bought me a 
(make a little break to play the B part, Chuck does, too, because it's a 4/4 beat) cute little toy