groups_check_slug( string $slug )

function groups_check_slug( $slug ) {
	$bp = buddypress();

	// First, make the proposed slug work in a URL.
	$slug = sanitize_title( $slug );

	if ( 'wp' == substr( $slug, 0, 2 ) )
		$slug = substr( $slug, 2, strlen( $slug ) - 2 );

	if ( in_array( $slug, (array) $bp->groups->forbidden_names ) )
		$slug = $slug . '-' . rand();

	if ( BP_Groups_Group::check_slug( $slug ) ) {
		do {
			$slug = $slug . '-' . rand();
		}
		while ( BP_Groups_Group::check_slug( $slug ) );
	}

	return $slug;
}