public static function dob($min = 18, $max = 100) {
		$dobYear = (int)date('Y') - (static::int($min, $max));

		$dobMonth = static::int(1, 12);

		if ($dobMonth == 2) {
			// leap year?
			if ($dobYear % 4 || $dobYear % 400) {
				$maxDays = 29;
			} else {
				$maxDays = 28;
			}
		} elseif (in_array($dobMonth, [4, 6, 9, 11])) {
			$maxDays = 30;
		} else {
			$maxDays = 31;
		}

		$dobDay = static::int(1, $maxDays);

		$dob = sprintf('%4d-%02d-%02d', $dobYear, $dobMonth, $dobDay);
		return $dob;
	}