I read about an egg on here saying that the bomb has 'Kiss it goodbye' written on it. I looked pretty thoroughly at the bomb, and maybe with the last update they changed it, because it's different now.

The best way to view this is to play a game of Assault on Beaver Creek alone. First, get the Sniper Rifle.Take the bomb, and go into one of the two bases where the bomb spawns (it doesn't matter which one because the level is symmetrical). Drop the bomb on top of the small, bridge-like thing in the room, then, while facing the bomb, walk down the ramp until the bomb is on eye-level, then zoom in on it with the Sniper Rifle. This gives you a perfect view of the bottom of the bomb, onto which is drawn Master Chief's head, a hand displaying the peace sign, then XOXO. What a pleasant gift from the Chief.