John P. Halo
As you may already know, the Massachusetts Institute of Technology has a long history of pranking (or hacks, as they call them) both on their own campus and at other schools. Though there have been some real winners over the years, this new one, captured today by MIT newspaper The Tech, really takes the cake.
To mark the Halo 3 release, MIT students gifted the John P. Harvard statue in Harvard Yard with a Spartan helmet (with "Master Chief in Training" written on the back) and an assault rifle. Love the nerds!