A stupid person.
A sideshow performer who hammers nails or similar items through his or her nostril into the nasal cavity; human blockhead.
To perform as a human blockhead.
To behave in a stupid manner.
A fool, a twit.
A small or puny person; one regarded as insignificant, contemptible.
A person who can be bullied playfully, or easily teased. Sometimes used as a pet-name (often for a younger sibling).