This happens when a dating couple try the long-distance relationship thing when they go off to university or college in September. Typically, when Thanksgiving rolls around and everyone goes home for the holiday, someone gets dumped. Hence the turkey drop.

When a college freshman breaks up with their long time steady on the first holiday vacation back home, usually at Thanksgiving.

A tragically botched up promotion or operation. This definition comes from an episode of "WKRP in Cincinatti" when the station dropped live turkeys from an airplane for a supermarket Thanksgiving Day promotion. Unfortunately, the crew didn't know that turkeys can't really fly and the birds dropped like lead weights onto the parking lot crowd.

An act of charity on the comedy show WKRP in Cinncinati when they drop turkey's on the poor people of the city

the onslaught of refuse that occurs after a particularly hearty meal, such as that of Thanksgiving.
There is the usual complication of everyone having the same symptom, but only a choice number of bathrooms. This fiasco can be referred to as the Turkey-Pants drop

n. A traditional act of charity during the Thanksgiving season, whereby you "drop off" a frozen "turkey" to some organization (like the Salavation Army), which then redistributes to the poor.