new.html

<a data-role="collapsible" data-theme="f" data-iconpos="right" data-collapsed-icon="arrow-d" data-expanded-icon="arrow-u" class="inline-collapsible dark-border">
	<h3>Categories</h3>
	<fieldset data-role="controlgroup">
	</fieldset>
</a>

new.html.erb

<div id="category-main-list">
	<a href="#" data-role="collapsible" data-theme="f" data-iconpos="right" data-collapsed-icon="arrow-d" data-expanded-icon="arrow-u" class="inline-collapsible dark-border category-list" 
		<h3>Categories</h3>
	</a>
	<fieldset data-role="controlgroup">
			<input id="category_2" name="profile[category_ids][]" type="checkbox" value="2" />
			<label for="category_2">Coil Tubing</label>
			<input id="category_7" name="profile[category_ids][]" type="checkbox" value="7" />
			<label for="category_7">Cranes</label>
			<input id="category_5" name="profile[category_ids][]" type="checkbox" value="5" />
			<label for="category_5">Fishing</label>
			<input id="category_8" name="profile[category_ids][]" type="checkbox" value="8" />
			<label for="category_8">Flow Back</label>
			<input id="category_10" name="profile[category_ids][]" type="checkbox" value="10" />
			<label for="category_10">Heavy Equipment</label>
			<input id="category_11" name="profile[category_ids][]" type="checkbox" value="11" />
			<label for="category_11">Misc</label>
			<input id="category_1" name="profile[category_ids][]" type="checkbox" value="1" />
			<label for="category_1">Pumps</label>
			<input id="category_4" name="profile[category_ids][]" type="checkbox" value="4" />
			<label for="category_4">Rentals</label>
			<input id="category_9" name="profile[category_ids][]" type="checkbox" value="9" />
			<label for="category_9">Trucking</label>
			<input id="category_6" name="profile[category_ids][]" type="checkbox" value="6" />
			<label for="category_6">Wireline</label>
			<input id="category_3" name="profile[category_ids][]" type="checkbox" value="3" />
			<label for="category_3">Workover Rigs</label>
	</fieldset>
</a>

some.js.coffee

$('#category-main-list a').on 'click', ->
  $(this).closest('fieldset').toggle()