A white elephant gift exchange or Yankee Swap is a Christmas party game found primarily in North America. Generally, white elephant parties need a minimum of six participants. With a larger group, game play may be more protracted. White elephant parties have been known to result in playful rivalries between players trying to get sought-after items. The goal of a white elephant party is usually to entertain rather than to gain.
The term "white elephant" refers to an extravagant but burdensome gift which cannot be easily disposed of, supposedly after the King of Siam gifted rare albino elephants to courtiers who had displeased him, that they might be ruined by the animals' upkeep costs.
A man selects a taken gift, while its previous owner is reluctant to relinquish it.
In its most basic form, the game is as follows: each participant supplies one wrapped gift. The gifts are placed in a central location, and participants determine in what order they will take turns selecting them. The first person opens a wrapped gift and the turn ends. On subsequent turns, each person can open a new present or gets the choice to "steal" another person's unwrapped gift. When a person's gift is stolen, that person chooses another wrapped gift to open. The game is over when the last person has taken their turn (but see variations below).
Gifts are typically inexpensive, humorous items or used items from home. The term white elephant refers to a gift whose maintenance costs exceed its usefulness. While the first use of this term remains a matter of contention among historians, one theory suggests that Ezra Cornell brought the term into the popular lexicon through his frequent social gatherings as early as 1828.
Since the process of stealing can prolong the game and can confer distinct disadvantages to certain places in the order of play, variations have arisen.
To speed up the multiple steals variant, there is often a certain number of steals allowed per turn. For example, after the third gift on a turn is stolen, the fourth player may be required to open a wrapped gift. An exception may be made for the last round (after all gifts have been opened), allowing an infinite amount of swapping (see below). Most of the time, variants which allow multiple steals end without completing the game as it becomes too difficult to track the game context. 
A certain gift may be particularly sought after, prolonging the game (almost indefinitely). To address this, two related variations have been widely adopted: First, no gift may be stolen more than once per turn. However, this gives a distinct advantage to the final participant. Because of this, a second common variation states that after a gift has been stolen a certain number of times (usually 3) it is "frozen" (or "dead" or "safe") and cannot be stolen again.
Another popular variant no longer places a limit on the number of times a gift can be stolen, but instead limits the number of times a person can be stolen from. Once the person reaches that number, the last gift they choose is automatically frozen to them. The frozen person can no longer be stolen from or steal from anyone else. The gifts themselves can circulate as often as possible unless frozen to someone, however a person cannot steal back the gift that was just taken from them.
Since the first player is the only one without the option of seeing any unwrapped gifts, some variations allow this player to take one final turn after all gifts have been opened and swap with any "unfrozen" gift.
One variation (usually only for games with serious gifts) is to mark gifts as suitable for males, females, or to both, to guide people into selecting a more appropriate gift.
Another variation is to leave all the gifts wrapped until the end. Stealing is still allowed (up to a pre-defined number of times) but must be done while the gifts are still wrapped. In this case, there is no stealing after the wrapping comes off.
Some versions vary the process of choosing the play order. For example instead of numbers from a hat, two decks of cards may be used to determine the picking order. Each deck is shuffled individually, and one of them is dealt to the players. One person flips the top card of the remaining deck, whoever has the first matching card then takes a gift. The cards are flipped again until another match is found, and that person is next to take a gift or takes someone else's unwrapped gift. This continues until everyone has had his or her turn. Dice are another way to determine who is allowed to "steal" a present, when the holder of the die roll doubles (2 of the same number) it is then their turn to take a gift.
One variation states that the gifts must not be purchased but, rather, the items must be things found lying around the house or the garage - things that are valuable but for which the owner has found no use.
Another option is to keep the gifts anonymous. In this case, standard-sized boxes may be used, or gifts may at least be wrapped inside-out (the white portion of wrapping paper showing) in order to help maintain the anonymity.
In another variation, the Host provides several extra wrapped packages that contain cards instead of gifts. Cards have instructions such as: pick two wrapped gifts, trade this card for the last wrapped gift, holder of this card cannot have their gift stolen (pick another gift). For every card that causes a player to keep two gifts, the Host provides an extra wrapped gift.
A more drastic variation involves giving gifts that are neither purchased nor desirable—essentially an "ugliest gift" or possibly "Old Maid" variation.
Since only desirable gifts will be stolen, people with less desirable gifts may be essentially out of the game after opening one. One variation to rectify this is to allow no stealing during the opening of gifts, but to have a subsequent stealing round in which the host secretly sets a timer, and everyone in the group takes turns trading their gifts with those of another. (Players may pass their turn.) This continues until the timer rings, at which time each player keeps what is in their hand.