scratch card 
noun
A card with a section or sections coated in an opaque waxy substance which may be scraped away to reveal a symbol indicating whether a prize has been won in a competition.She is advising people that if someone approaches them in the resort with a scratch card and this reveals a prize, they should walk away....
- A part of the campaign will also involve exciting offers in which customers can win fab gifts through scratch cards at all outlets running the contest.
- The two cellular phone companies have the dollar denomination symbol on air time scratch cards sold to their subscribers.