"Thou Swell" is a show tune, a popular song and a jazz standard.
The music was written by Richard Rodgers, with words by Lorenz Hart, for the 1927 musical A Connecticut Yankee. There are jazz vocal renditions by Nat King Cole, Sarah Vaughan, Frank Sinatra, Blossom Dearie, Ella Fitzgerald and Joe Williams. Fats Waller and Billy May both recorded the song instrumentally.
The lyric is notable, as indicated by the title, for its mix of old English and modern slang.
The music of the song is featured in the film All About Eve (1950). It is played on the piano at the party when Margo tells her friends to "fasten their seat belts".
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http://en.wikipedia.org/wiki/Thou_Swell
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He:

Babe, we are well met,
As in a spell met,
I lift my helmet,
Sandy; You're just dandy.
For just this here lad.
You're such a fistfull.
My eyes are mistful,
Are you too wistful to care,
Do say you care to say;
"Come near lad."
You are so graceful,
have you wings?
You have a face full of nice things;
You have no speaking voice, dear,
With ev'ry word it sings

Refrain:

Thou swell! Thou witty!
Thou sweet! Thou grand!
Wouldst kiss me pretty?
Wouldst hold my hand?
Both thine eyes are cute too;
What they do to me.
Hear me holler I choose a Sweet lollapaloosa in thee.
I'd feel so rich in a hut for two;
Two rooms and a kitchen I'm sure would do;
Give me just a plot of,
Not a lot of land,
And Thou swell! Thou Witty! Thou Grand!

She:

Thy words are queer, Sir,
Unto mine ear, Sir,
Yet thou'rt a dear, Sir, to me;
Thou could'st woo me;
Now could'st though try, knight.
I'd murmur "Swell", too,
And like it well too;
More thou wilt tell to Sandy.
Thou art dandy;
Now art though my knight.
Thine arms are martial;
Thou hast grace;
My cheek is partial to they face;
And if they lips grow weary,
Mine are resting place.

Refrain:

Thou swell! Thou witty!
Thou sweet! Thou grand!
Wouldst kiss me pretty?
Wouldst hold my hand?
Both thine eyes are cute too;
What they do