One of ours is the good ol "hotdogged". It's when someone leaves their computer unlocked, we will open their email and send out an email from their account. It talks about how much they love hotdogs.
Then they get the hotdog stuffed toy.
We also have a company wide capture the flag nerf battle. Cali has come to phoenix multiple times and takes the flag home, so we have to go up there and get it.