It's nice to have chords, and it's nice to have that German foolishness in that other thread, but it's also nice to have verified, authentic lyrics. Here they are, in all their glory:

RUBBER DUCKIE
(Jeff Moss)

Rubber Duckie, you're the one!
You make bath time lots of fun.
Rubber Duckie, I'm awfully fond of you;
(voh voh voh, dee oh!)

Rubber Duckie, joy of joys,
When I squeeze you, you make noise!
Rubber Duckie, you're my very best friend, it's true!

CHORUS
Oh, every day when I
Make my way to the tubby
I find a little fella who's
Cute and yella and chubby
(rub-a-dub-dubby!)

Rubber Duckie, you're so fine,
And I'm lucky that you're mine.
Rubber Duckie, I'm awfully fond of you.

CHORUS

Rubber Duckie, you're so fine
And I'm lucky that you're mine
Rubber Duckie, I'd like a whole pond of -
Rubber Duckie, I'm awfully fond of you!
(doo doo, be doo.)

© 1970 Festival Attractions, Inc. Copyright renewed. Sung by Ernie (voiced by Jim Henson)

http://www.sesamestreet.org/parents/theshow/watch/classicclips#ff3ce886-1558-11dd-a62f-919b98326687