function my_custom_loop_2 ($category, $tag, $offset) {
        $args=array(
          // showposts has been replaced, use 'posts_per_page' instead
          // 'showposts'        =>1,
          'posts_per_page'      => 3,
          // this has been replaced, use 'ignore_sticky_posts'
          // 'caller_get_posts' => 1,
          'ignore_sticky_posts' => true,
        );

        if ($category) {
          $args['cat'] = $category;
        }

        if ($tag) {
          $args['tag'] = $tag;
        }

        if ($offset) {
          $args['offset'] = $offset;
        }

        $my_query = new WP_Query($args);
        // ... rest of function to output loop

if( $my_query->have_posts() ) {
            while ($my_query->have_posts()) : $my_query->the_post(); ?>
             <div class="three-titles">
              <a href="<?php the_permalink() ?>" ><?php the_title(); ?></a></br>
             </div>
            <?php
            endwhile;
        } //if ($my_query)

        wp_reset_query();  // Restore global post data stomped by the_post().
 };

<?php my_custom_loop_3(13, NULL, 1); ?>