The classic by Rodgers and Hart. 

 My funny valentine, sweet comic valentine,
You make me smile with my heart.
Your looks are laughable, unphotographable,
Yet you're my favorite work of art.

Is your figure less than Greek?I
Is your mouth a little weak?
When you open it to speak are you smart?

But don't change a hair for me, not if you care for me.
Stay little valentine stay!
Each day is Valentines day.