I learned this Italian card game from David Chudzicki and have played it primarily with my cousins. It's the best five person card game I know, and I enjoy it about as much as bridge, though for different reasons.

Basic Idea: Five players end up through a bidding process divided into two teams: the jaguar and their friend against the other three. While everyone knows who the jaguar is, their friend remains secret until choosing to reveal themself. Cards have point values totaling 120, and if the jaguar and friend get more than half they win the hand.

Set Up and Card Values: Take an italian deck of cards or a normal deck with the 10s, 9s, and 8s removed. A dealer deals out five hands, which will come to eight cards each. Which player is the dealer progresses around the circle each hand. The cards are ordered "A, 3, K, Q, J, 7, 6, 5, 4, 2" and are worth points as:

Number	Value
A	11	"big points"
3	10
K	4	"small points"
Q	3
J	2
<=7	0	"junk"

Bidding: The dealer begins with either bidding or passing, as does each player in turn around the circle repeatedly until some bid has not been topped. Once you have passed you may not bid again that hand. Bidding begins with the highest card, the A, and proceeds down from there (3, K, Q, ...). [Update 2013-04-29: bidders may skip cards. This is most common when the bidder has the card in question. So if you had strong clubs to the 3, K, Q and the bidding before you were "A, 3", you would probably bid "J".] No suits are involved in the bidding. Once bidding is complete, the winner of the bidding is the jaguar. The jaguar names a suit to be trump and the player with the card of the winning value in the named suit is the friend. Note that if the jaguar names a card in their own hand, the jaguar and the friend are the same player. Scoring is slightly different in this case, as you will see below.

Play: Play consists of eight tricks. A trick is a card being led, then each player in turn around the circle plays any of their cards. Bridge, hearts, and spades players should forget those games' rules about following suit. The winner of the trick is the player with the highest played trump card, or if no trump were played the highest card in the led suit. Example: clubs are trump. Player A leads the 6 of diamonds. Players B, C, and D play the 3, 4, and 5 of diamonds respectively. Player E plays the 2 of clubs. Because clubs are trump, player E would win the trick. If clubs were not trump, player B would win the trick. (Remember that 3s are high). Winning a trick means that that player gets the cards contained (which one cares about only for their point values) and leads for the next trick. Update 2012-08-10: the jaguar leads for the first trick.

Scoring: By the end of the game, all cards have been played and so it is known to all who is the friend and who is not. The point sum for the friend and the jaguar is then compared to the point sum for the other three players, and the winner is the group with more points. The jaguar and friend lose ties. Points are awarded: 2 to the jaguar, one to everyone else. If you win your points are positive, if you lose your points are negative. So on a jaguar victory, the jaguar gets +2, the friend gets +1, the other three each get -1. In the rare case of the jaguar and the friend being the same player, the jaguar gets 4 points while the other four players each get 1. Note that this game is completely zero sum, so players will generally keep running totals across hands. Among well matched players, people will often keep these totals across games with different players.

Table Talk: During the game, table talk is allowed, encouraged, and essential. The jaguar gives instructions to their friend, whoever they may be, often starting with "please don't reveal who you are until I tell you to." The other four all claim not to be the friend and tell each other what to do, arguing about how best to divide points to defeat the jaguar. New players can often learn the game by just playing with four experienced ones and being told what to do without any out-of-game rule explanation. People will probably lie to each other, and this is not prohibited. Lying about the rules, though, is metagaming and is prohibited.

Update 2013-04-29: It turns out another name for this game is Briscola Chiamata.