<p>Sass 3.2 added the <a href="http://sass-lang.com/documentation/file.SASS_REFERENCE.html#mixin-content"><code>@content</code> directive</a>, which allows
us to pass a content block into a mixin.</p>

<pre><code>@mixin apply-to-ie6-only {
* html {
@content
}
}

@include apply-to-ie6-only {
#logo {
background-image: url(/logo.gif);
}
}
</code></pre>

<p>Generates:</p>

Read more at the source