title: jQuery Validate Plugin - How to create a simple custom rule?
body: <p>How do you create a simple, custom rule using the jQuery Validate plugin (using <a href="http://jqueryvalidation.org/jQuery.validator.addMethod" rel="noreferrer"><code>addMethod</code></a>) that doesn't use a regex?</p>
  
  <p>For example, what function would create a rule that validates only if at least one of a group of checkboxes is checked?</p>