Do you mean the poem by Edward Lear? If so, the rhyme scheme fits the following pattern:

Said the Duck to the Kangaroo,  A
    'Good gracious! how you hop!  B
Over the fields and the water too,  A
    As if you never would stop!  B
My life is a bore in this nasty pond,  C
And I long to go out in the world beyond!  C
    I wish I could hop like you!'  A
    Said the duck to the Kangaroo.  A

In the subsequent stanzas, this rhyme scheme is repeated - the first and third lines rhyme, the second and fourth lines rhyme, a different rhyme is introduced in the fifth line and this line rhymes with the sixth. The seventh and eighth lines are a couplet and they each end with the sound of the first line rhyme "A". In every stanza, the couplet is "A". So, you can do the rest yourself:

'Please give me a ride on your back!'  D
    Said the Duck to the Kangaroo.  A
'I would sit quite still, and say nothing but "Quack,"  D
    The whole of the long day through!  A
And we'd go to the Dee, and the Jelly Bo Lee,  E
Over the land and over the sea;--  E
    Please take me a ride! O do!'  A
    Said the Duck to the Kangaroo.  A

See how the "A" rhyme ends each stanza?

I believe this cute little poem has a deeper meaning. It shows how the duck and the kangaroo resolve some very unique differences to get along and accomplish their goals. They work out the obstacles to their trip in unique ways and they are able to hop around the world three times together, having a grand old time.

Wouldn't it be nice if we humans could do the same thing? We would not have wars!