When a student returning from college breaks up with their significant other from high school. So-called because it traditionally takes place over thanksgiving break, the first time most students return from college.
When Jim and Heather came home for Thanksgiving, she gave him the turkey dump.
Mostly in Canada, when a girlfriend or boyfriend comes back from uni/collage and they dump you over the thanksgiving weekend. Usually because they've met someone at uni/collage.
"My weekend sucks"
"why? its Thanksgiving aren't you thankful that you still have your girlfriend?"
" No man, she turkey dumped me!"
" lame. hope the mash potatoes and gravy sticks on her"