How close can I come with a parody without infringing on a copyright?

[bird]

I would like to animate a parody of:
http://en.wikipedia.org/wiki/Let's_All_Go_to_the_Lobby

I'd have original lyrics/music/characters/setting.

Any opinions?

Thanks guys!

 

[Zensteve]

I'm pretty sure that's public domain, even though from the 50's.

Checking.

 

[bird]

I'm pretty sure that's public domain, even though from the 50's.

Checking.

Thanks Zen! You're right, Creative Commons: Public Domain. Yay!