time = Time.new
current_time = time.hour.to_i

meal_type = "none"
if current_time >= 14 && current_time <= 18
  meal_type = "dinner"
elsif current_time >= 0 && current_time <14
  meal_type = "lunch"
end

...

if meal_type == "none"
  message = "Sorry, the ordering service is not available now. You can make lunch orders between 12:00am-14:00pm and dinner orders between 14:00pm-18:00pm."
else
  message = "Here is today's #{meal_type} menu: 1. Fried Chicken Bento($8), Rosetea Cafe 2. Stew Beef on Rice($7), Orient Express 3. Shrimp Curry($10), Sichuan Gourmet. Which one would you like to choose? "
end