So. This is... strange. Apparently, there's an easter egg hidden in one of the Call of Duty: Modern Warfare 3 multiplayer maps -- Mission, to be precise -- that gives you a look at a snarling bear dressed in a tutu. It's a flat 2D image that you can only see using a free camera in spectator mode, but... yeah. It's a bear in a tutu. And it doesn't look happy.
I've tested and verified this for myself using the Xbox 360 version of the game. Like the speaker in the above video tutorial, I'm not exactly sure what the significance of this extremely odd thing is. But it's totally there, and totally weird, so go ahead and check it out.
Source: Se7enSins.com forums