Where are some cheaper places to eat lunch at or restaurant coupons?

I always take my friend out for lunch on her birthday, but this year I am trying to conserve money. I can afford to take her out..... I would just rather go somewhere a little cheaper. Are there any coupons out there for places? I'm open to just about anything. Just trying to save as much money as possible. I've become a very frugal person the last year and hate spending full price for anything!!