The sexist definition in the dictionary describes a sexist as a person who shares sexist beliefs and participates in sexist behaviors. Sexist beliefs are beliefs that revolve around sexism. The word sexist can describe the nature of a comment or gesture, as well.
So how long do they typically last? Well, standard copper plugs are said to last anywhere from 10,000 to 20,000 miles (16,093 to 32,187 kilometers), while more expensive iridium or platinum spark plugs can last 60,000 miles (96,561 kilometers) or more [source: Spark plugs UK].
Thread one of the new plugs into the spark plug hole until you can no longer turn it with your fingers, then use a torque wrench to tighten it to the specification listed in your service manual. It is a good idea to slip a short length of rubber hose over the end of the plug to use as a tool to thread it into place.