As I was sitting in a chair
I knew the bottom wasn't there,
Nor legs, nor back -- but I just sat
Ignoring little things like that.

(Don't know source.)

One of Dorothy Parker's most famous:

Men never make passes
at girls who wear glasses.

Another source unknown:

A wonderful bird is the pelican
His beak can hold more than his belly can.
He can hold in his beak
Enough food for a week!
I wonder how in the hell 'e can.