Even if the song is sung acapella, the chords fit in quite nicely.
You can also try singing the actual bass notes onto the song.
(same chords for every verse)

C5                     G5                    G5                   C5
If you miss me at the back of the bus, and you can't find me nowhere 
F5                   C5                 G5                    C5
Come on over to the front of the bus, I'll be ridin' right there 
C5                    G5
I'll be ridin' right there 
G5                    C5
I'll be ridin' right there 
           F5                   C5  
You got to come on over to the front of the bus 
G5                    C5
I'll be ridin' right there 

C5                     G5                  G5                   C5
If you miss me at the cotton fields, and you can't find me nowhere 
F5                    C5          G5                     C5
Come on down, to the jailhouse, I'll be roomin' right there 
C5                     G5
I'll be roomin' right there 
G5                     C5
I'll be roomin' right there 
F5                   C5
Come on down to the jailhouse 
G5                     C5
I'll be roomin' right there 

C5                     G5                      G5                   C5
If you miss me in the Mississippi River, and you can't find me nowhere
F5                   C5           G5                    C5
Come on over to the city' pool, I'll be bathin' right there 
C5                     G5
I'll be bathin' right there 
G5                     C5
I'll be bathin' right there 
F5                   C5
Come on over to the city' pool 
G5                     C5
I'll be bathin' right there 

C5                     G5                 G5                 C5
If you miss me at the picket lines, and you can't find me nowhere 
F5                         C5      G5                    C5
Come on down to the court house, I'll be votin' right there 
C5                    G5
I'll be votin' right there 
G5                    C5
I'll be votin' right there 
F5                   C5
Come on down to the courthouse 
G5                    C5
I'll be votin' right there 

[Verse 1 again]