Who has to show cards after 5th street?

My friends are arguing about who HAS to show after 5th street bets. I have heard that only the person that gets called HAS to show, and of course the person with the best hand that wins the pot HAS to show. But, if you call a bet and get beat, do you HAVE to show your cards??

Nick

The player who is last to bet / raise is the first player to show.

After that the other players will show / muck in order.

I thought the first person that bets HAS to show because whoever calls him is paying to see his cards. Then if the second guy is beat, he can just throw his cards away.

As he said, last to BET not call

As stated, the last person to bet/raise must show his cards. The rest of the callers do not have to show unless they have the same or better hand.