Quickly kill all spam and pending comments in WordPress (caveat emptor)

gistfile1.php

function kill_pending_and_spam() {
	$currentScreen = get_current_screen();
	if ( 'edit-comments' == $currentScreen->id ) {
		global $wpdb;

		$query = $wpdb->prepare( "DELETE FROM $wpdb->comments WHERE comment_approved = 0", '' );
		$wpdb->query( $query );

		$query = $wpdb->prepare( "DELETE FROM $wpdb->comments WHERE comment_approved = 'spam'", '' );
		$wpdb->query( $query );
	}
}
add_action( 'current_screen', 'kill_pending_and_spam' );