As we talked about on page 1, the reverse next call is used when your partner dealt and turned down a suit. Here is your opportunity to name trump from the second seat.
Your partner is the dealer sitting in the North seat. They just dealt and turned up the 9 of hearts. Bidding is passed around and your partner turns down the 9.
The player in East had a strong hand in hearts and was hoping the dealer would pick up the 9, but no, not this time. East seat again passes, deciding not to try a 'next call'. Now it is your turn(S) to bid. Yes, you hold a junk hand, but you know your partner is a strong player and expects you to name trump when possible.
You think about it for a second then call spades. East senses weakness in your call and because they hold a couple of aces they lead the 9 of trump. There are times when it's acceptable to break the rules and lead trump. This could be one of those times. You (S) play the 10 of spades, East shows void and your partner (N) takes the trick with the king.
Had you passed West would most likely have called diamonds. Depending on how the cards were played, they may have made a point. Even worst is the fact that your partner would have been left holding a great hand, but in the wrong color.
All too often players give up points because they only consider what is in their hand when naming trump. Experienced players are always looking for clues as to what cards their partner holds. One such clue is when your partner is the dealer and passes first round. Obviously, that means he has no strength in the suit that was turned-up. You may take that a step farther to mean he has no strength in any suit of that color. Winning at euchre involves taking risks.