I know of three types of turkey drops:

Gambling

Simply put, this is a minor variation of the chicken drop, which was immortalized in song in the 1980s by Mojo Nixon. Don't confuse it with the sleight-of-hand money-holding scam called the pigeon drop; this particular drop is bird-shit keno at its finest. Gamblers pay to pick numbered squares in a turkey pen that they hope will contain a dollop of bird droppings by the end of the game. The lone turkey wanders around an area that is enclosed, but spacious enough to present a lot of potential targets to sell to bettors. This is considered by some cultures to be an exciting and enjoyable way to gamble. In fact, some agriculturally inclined communities have been known to stage some sort of guano keno as a way to raise money for local high schools. I'm no PETA freak or anything, but this sort of game looks to me like cockfighting for people who've lost the will to live.

Gravity

It has been claimed that at least a couple of American radio stations have staged promotions involving the dropping of live turkeys from moving cars or flying airplanes, with disastrous consequences (the turkey being a flightless bird, and all) that were somehow unforseen by the parties involved. One of the more famous versions of this urban legend claims that the radio station was WQXI in Atlanta, which regularly served as inspiration to the writers of WKRP In Cincinnati. As a result, the gag made it into the show's seventh episode, titled "Turkeys Away". Les Nessman describes the unfolding horror with a nod to the Hindenberg disaster: "Oh the humanity! The turkeys are hitting the ground like sacks of wet cement!"

College Dating

During the freshman year of college in America, it is extremely common for couples to break up over Thanksgiving break, no matter how long they thought they'd be together at the beginning of the relationship. Much of this is simply due to hormone-addled lust and the sudden rush of freedom that comes during the first few months away from home (aah, memories). However, three months into the relationship, typically around Thanksgiving time, limerance has worn off, and the immaturity, selfishness, and shallowness of each person's mate are suddenly much harder to overlook.

Even couples who have been dating each other since high school are not immune from the turkey drop, especially if they are in a long-distance relationship because they don't attend college together. In those cases, one of them decides it is better to wait to discuss the break-up until they are both back home for the holiday weekend.