A pretty funny song by the comedy acappella group Da Vinci's Notebook.

           E            Ab
Whenever life gets you down
             A       Am
Keeps you wearing a frown
          B     Bb       A       Ab  E
And the gravy train has left you behind
               E          Ab
And when your all out of hope
             A           Am
Down at the end of your rope
       F#                          B
And nobody's there to throw you a line

        A
If you ever get so low
                Am
That you don't know which way to go
     E                         E7
Come on and take a walk in my shoes
       F#
Never worry 'bout a thing
 F#  Ab   A
Got the world on a string
            B                          
Cause I've got the cure for all of my blues (all of his blues)

                 E          Ab  C#m
I take a look at my enormous penis
          A               B       E   E   Eb   E
And my troubles start a-meltin' away (ba-doom bop)
                 E          Ab  C#m
I take a look at my enormous penis
          F#                       B
And the happy times are comin' to stay (be-doo)

         A
I got a sing and I dance
         Am
When I glance in my pants
        E                        Eb  C#m
And a-feelin's like a sun shiny daaaaay
                 A          B  E   Eb D  C#m
I take a look at my enormous  Pee--e--e--nis
          A          B        E   E   Eb   E
And a-everything is goin' my way (ba-doom bop)


And that's basically it. The rest of the song uses 
the same chords. Just listen to it and you should 
figure out the structure.