$user = new User();

$user->nome = $request->nome;
$user->sobrenome = $request->sobrenome;
$user->email = $request->email;
$user->password = bcrypt($request->password);
$user->slug = str_slug($request->nome . ' ' . $request->sobrenome, '-');

try {
     $user->save();
} catch (Exception $e) {
     $user->slug = str_slug($request->nome . ' ' . $request->sobrenome . RAND(111111, 999999), '-');

     $user->save();
}