"A collection of insults 19" joke

A medical mystery.
A mental midget with the IQ of a fencepost. - Tom Waits
A mind as empty as the sleeping pill concession at a honeymoon hotel.
A mind like wet tennis shoes… Makes squishy noises when running.
A modest little person, with much to be modest about. - Churchill
A natural talent for finding subliminal messages in ice cubes.
A Neanderthal brain in a Cro-Magnon body.
A notch off the timing mark.
A one-bit brain with a parity error.
A pacifist out of necessity in a battle of wits.
A photographic memory, but the lens cover is glued on.
A prime candidate for natural deselection.
A quart low.
A return with no gosub.
A room temperature IQ.