The Hard Rock Cafe is famous all around the world. Mystery shopping them is a great experience...
I have been lucky enough to get this assignment a few times, and I would have to say it has been one of my very favourites.
If you are interested in free dinner for 2, drinks, and a gift shop purchase, plus getting paid $40 (US) then you should register with the Market Research Company that conducts their Mystery shopping.
Their name is Freeman Group Solutions. If you are interested contact them here with an email that says you interested in doing mystery shops and tell them the Hard Rock Cafe that is in your area.