What does it mean to "look at someones cards"?

Question

What does it mean to "look at someones cards"?

Answer 1

When you play card games you are supposed to keep your cards to yourself.  Someone who looks at your cards is cheating.  So that person is sneaky and a cheater.

Answer 2

Someone who doesn't hold his cards close to his vest (as the saying goes). So, therefore holds no secrets.