How to get excerpt of the recent posts

You can use the wp_trim_excerpt() to get the excerpt of the content.

You can use it inside your loop to get the excerpt of each post

the string provided to a maximum of 55 words if it is more then a […] will be added to the end of the string.

<?php
    $recent_posts = wp_get_recent_posts(array('post_type'=>'jokes'));
    foreach( $recent_posts as $recent ){
        echo '<li><a href="' . get_permalink($recent["ID"]) . '" title="Look '.esc_attr($recent["post_title"]).'" >' .   $recent["post_title"].'</a> </li> ';
        $excerpt = wp_trim_excerpt( $recent['post_content']); // $excerpt contains the excerpt of the concerned post
        echo $excerpt;
    }
?>