Last Checkin Chicken
In the lifetime of every single project I've ever worked on, there's this little "game" that's informally played at the very end of the ship cycle. It's never been formalized, but it's always been played (at least it was in every group I've ever worked in).
I call it "Last Checkin Chicken", it's kinda like the childrens game of "Hot Potato".
The way the game works is that no group wants to be the last group that makes a checkin in a particular release of the product. I've never really understood why this is, maybe it's because we could have shipped one day earlier if it hadn't been for that darned last bug (which is silly, but).
Since nobody wants to make the last checkin, whenever you make a checkin, you hold your breath and hope and pray that somebody else makes a checkin (and thus your checkin isn't the last one in the product). If you ARE the last person making a change, then you don't win a prize or have to wear goat horns, or anything, it's just an invisible badge of shame :)
Last Checkin Chicken has varients. Some groups hold informal office pools about which group is going to be the one that makes the last checkin ("Heh, I bet it's going to be the Glibert team, their code is just garbage", "Nah, it's going to be Snorklewanger team, they always find stuff at the last minute"). And within the individual teams, there is even further speculation, either by feature ("I know we've had trouble with the FLOMBERT feature, if it's our team that has the last bug, it's going to be in that feature") or developer ("Man, Terry writes crappy code, bet the last fix is in code he wrote").
Ultimately, Last Checkin Chicken is something that developers do during the somewhat tense final hours of a project as a strange way of blowing off steam, ultimately it's harmless.